{"id":35434,"date":"2022-09-14T09:50:36","date_gmt":"2022-09-14T04:20:36","guid":{"rendered":"https:\/\/apboardsolutions.guru\/?p=35434"},"modified":"2022-09-14T09:50:36","modified_gmt":"2022-09-14T04:20:36","slug":"ap-inter-1st-year-chemistry-study-material-chapter-9","status":"publish","type":"post","link":"https:\/\/apboardsolutions.guru\/ap-inter-1st-year-chemistry-study-material-chapter-9\/","title":{"rendered":"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements"},"content":{"rendered":"<p>Andhra Pradesh BIEAP <a href=\"https:\/\/apboardsolutions.guru\/ap-inter-1st-year-chemistry-study-material\/\">AP Inter 1st Year Chemistry Study Material<\/a> 9th Lesson The s-Block Elements Textbook Questions and Answers.<\/p>\n<h2>AP Inter 1st Year Chemistry Study Material 9th Lesson The s-Block Elements<\/h2>\n<p><span style=\"color: #0000ff;\">Very Short Answer Questions<\/span><\/p>\n<p>Question 1.<br \/>\nGive reasons for the diagonal relationship observed in the periodic table.<br \/>\nAnswer:<\/p>\n<ul>\n<li>Diagonal relationship is due to similar sizes of atoms (or) ions<\/li>\n<li>Diagonal relationship is due to similar electro negativities of the respective elements. Diagonally similar elements possess same polarising power.<\/li>\n<li>Polarizing Power = \\(\\frac{\\text { ionic charge }}{\\text { (ionic radius) }^2}\\)<\/li>\n<\/ul>\n<p>Question 2.<br \/>\nWrite completly the electronic configurations of K and Rb.<br \/>\nAnswer:<br \/>\nThe electronic configuration of &#8216;K&#8217; is 1s<sup>2<\/sup> 2s<sup>2<\/sup> 2p<sup>6<\/sup> 3s<sup>2<\/sup> 3p<sup>6<\/sup> 4s<sup>2<\/sup><br \/>\nThe electronic configuration of &#8216;Rb&#8217; is 1s<sup>2<\/sup> 2s<sup>2<\/sup> 2p<sup>6<\/sup> 3s<sup>2<\/sup> 3p<sup>6<\/sup> 4s<sup>2<\/sup> 3d<sup>10<\/sup> 4p<sup>6<\/sup> 5s<sup>1<\/sup>.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 3.<br \/>\nLithium salts are mostly hydrated. Why ?<br \/>\nAnswer:<br \/>\nHydration enthalpy of Li<sup>+<\/sup> ion is very high. It has very high degree of hydration. So &#8216;Li&#8217; salts are mostly hydrated.<br \/>\nEg : LiCl . 2H<sub>2<\/sub>O.<\/p>\n<p>Question 4.<br \/>\nWhich of the alkali metals shows abnormal density ? What is the order of the varia-tion of density among the IA group elements.<br \/>\nAnswer:<\/p>\n<ul>\n<li>&#8216;K&#8217; has abnormal density among alkalimetals due to high inter atomic distances in crystal lattice.<\/li>\n<li>The order of the variation of density among the IA group elements as follows.<br \/>\nLi &lt; Na &gt; K &lt; Rb &lt; Cs.<\/li>\n<\/ul>\n<p>Question 5.<br \/>\nLithium reacts with water less vigorously than sodium. Give your reasons.<br \/>\nAnswer:<br \/>\nLithium reacts with water less vigorously than sodium.<\/p>\n<p>Reasons :<\/p>\n<ul>\n<li>Lithium has small size.<\/li>\n<li>Lithium has very high hydration energy.<\/li>\n<\/ul>\n<p>Question 6.<br \/>\nLithium Iodide is the most covalent among the alkali metal halides. Give the reasons.<br \/>\nAnswer:<br \/>\nLithium iodide is the most covalent among the alkalimetal halides.<\/p>\n<p>Reasons :<\/p>\n<ul>\n<li>The polarising capability of lithium ion is high.<\/li>\n<li>Li<sup>+<\/sup> ion has very small size.<\/li>\n<li>Li<sup>+<\/sup> ion has high tendency to distort electron cloud around the iodide ion.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 7.<br \/>\nIn what respects lithium hydrogen carbonate differs from other alkali metal hydrogen carbonates.<br \/>\nAnswer:<br \/>\nLithium hydrogen carbonate cannot exist in solid form but remaining alkali metal hydrogen carbonates exist as solids.<\/p>\n<p>Question 8.<br \/>\nWrite the complete electronic configurations of any two alkaline earth metals.<br \/>\nAnswer:<\/p>\n<ol>\n<li>The electronic configuration of &#8216;Mg&#8217; is 1s<sup>2<\/sup> 2s<sup>2<\/sup> 2p<sup>6<\/sup> 3s<sup>2<\/sup><\/li>\n<li>The electronic configuration of &#8216;Ca&#8217; is 1s<sup>2<\/sup> 2s<sup>2<\/sup> 2p<sup>6<\/sup> 3s<sup>2<\/sup> 3p<sup>6<\/sup> 4s<sup>2<\/sup>.<\/li>\n<\/ol>\n<p>Question 9.<br \/>\nTell about the variation of m.pts., and b.pts among the alkaline earth metals.<br \/>\nAnswer:<\/p>\n<ol>\n<li>The m.pts and b.pts of alkaline earth metals are higher than corresponding alkali metals due to smaller sizes.<\/li>\n<li>Due to low I.P. values the variation of m.pts and b.pts among alkaline earth metals is not sys-tematic.<\/li>\n<\/ol>\n<p>Question 10.<br \/>\nWhat are the characterstic colours imparted by the HA elements ?<br \/>\nAnswer:<br \/>\nElements &#8211; Imparted colours towards flame<br \/>\nCalcium &#8211; Brick red<br \/>\nStrontium &#8211; Crimson red<br \/>\nBarium &#8211; Apple green<br \/>\nBeryllium &#8211; No colour<br \/>\nMagnesium &#8211; No colour<\/p>\n<p>Question 11.<br \/>\nWhat happens when magnesium metal is burnt in air ?<br \/>\nAnswer:<br \/>\nMagnesium metal burns with dazzling brilliance in air to give MgO and Mg<sub>3<\/sub>N<sub>2<\/sub>.<br \/>\n2 Mg + O<sub>2<\/sub> \u2192 2 MgO<br \/>\n3 Mg + N<sub>2<\/sub> \u2192 Mg<sub>3<\/sub>N<sub>2<\/sub>.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 12.<br \/>\nLithium carbonate is not so stable to heat as the other alkali metal carbonates. Explain.<br \/>\nAnswer:<br \/>\nLithium carbonate is not so stable to heat because Lithium has very small size and it polarises the large CO<sub>3<\/sub><sup>-2<\/sup> ion which leads to the formation of more stable Li<sub>2<\/sub>O and CO<sub>2<\/sub>.<br \/>\nAs the electro positive character increases down the group, the stability of carbonats increase.<\/p>\n<p>Question 13.<br \/>\nWrite a balanced equation for the formation of ammoniated IIA metal ions from the metals in liquid ammonia.<br \/>\nAnswer:<br \/>\nAlkaline earth metals dissolve in liquid ammonia to give deep blue black solutions forming ammoniated ions.<br \/>\nM + (x + y) NH<sub>3<\/sub> \u2192 [M(NH<sub>3<\/sub>)<sub>x<\/sub>]<sup>2+<\/sup> + 2 [e(NH<sub>3<\/sub>)<sub>y<\/sub>]<sup>&#8211;<\/sup><br \/>\nFrom the above solutions, ammoniates [M(NH<sub>3<\/sub>)<sub>x<\/sub>]<sup>2+<\/sup> can be recovered.<\/p>\n<p>Question 14.<br \/>\nThe fluorides of alkaline earth metals are relatively less soluble than their respective chlorides in water. Why ?<br \/>\nAnswer:<br \/>\nBecause of their high lattice energies fluorides of alkaline earth metals are relatively less soluble than their respective chlorides in water.<\/p>\n<p>Question 15.<br \/>\nWhat happens when hydrated Mg (NO<sub>3<\/sub>)<sub>2<\/sub> is heated ? Give the balanced equation.<br \/>\nAnswer:<br \/>\nWhen hydrated Mg(NO<sub>3<\/sub>)<sub>2<\/sub> is heated, it first loses the six water molecules and on further heating<br \/>\ndecomposes to give the oxide.<br \/>\n2 Mg (NO<sub>3<\/sub>)<sub>2<\/sub> \u2192 2 MgO + 4NO<sub>2<\/sub> + O<sub>2<\/sub>.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 16.<br \/>\nWhy does the solubility of alkaline earth metal hydroxides in water increases down the group ?<br \/>\nAnswer:<br \/>\nAmong alkaline earth metal hydroxides, the anion being common the cationic radius will influence the lattice enthalpy. Since lattice enthalpy decreases much more than the hydration enthalpy with increasing ionic size, the solubility increases as we go down the group.<\/p>\n<p>Question 17.<br \/>\nWhy does the solubility of alkaline earth metal Carbonates and sulphates in water decrease down the group ?<br \/>\nAnswer:<br \/>\nThe size of anions being much larger compared to cations, the lattice enthalpy will remain almost constant within a particular group. Since the hydration enthalpies decrease down the group, solubility will decrease as found for alkaline earth metal carbonates and sulphates.<\/p>\n<p>Question 18.<br \/>\nWrite the average composition of Portland cement.<br \/>\nAnswer:<br \/>\nComposition of port land cement is<br \/>\nCao &#8211; 50 &#8211; 60%<br \/>\nSio<sub>2<\/sub> &#8211; 20 &#8211; 25%<br \/>\nAl<sub>2<\/sub>O<sub>3<\/sub> &#8211; 5 &#8211; 10%<br \/>\nMgo &#8211; 2 &#8211; 3%<br \/>\nFe<sub>2<\/sub>O<sub>3<\/sub> &#8211; 1 &#8211; 2% and<br \/>\nSO<sub>2<\/sub> &#8211; 1 &#8211; 2%<\/p>\n<p>Question 19.<br \/>\nWhy is gypsum added to cement ?<br \/>\nAnswer:<br \/>\nGypsum is added to cement to slow down the process of setting of the cement and to get sufficiently hardened cement.<\/p>\n<p>Question 20.<br \/>\nWhy are alkali metals not found in the free state in nature ? [Mar. 13]<br \/>\nAnswer:<br \/>\nAlkali metals are not found in the free state in nature because they readily lose their valency electron to form M<sup>+<\/sup> ion (a nonvalent ion).<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 21.<br \/>\nPotassium carbonate cannot be prepared by Solvay process. Why ?<br \/>\nAnswer:<br \/>\nPotassium carbonate cannot be prepared by solvay process because potassium bi carbonate is more soluble and to be precipitated by the addition of ammonium bi carbonate to a saturated solution of potassium chloride.<\/p>\n<p>Question 22.<br \/>\nDescribe the important uses of caustic soda.<br \/>\nAnswer:<br \/>\nUses:<\/p>\n<ul>\n<li>It is used in petrol refining<\/li>\n<li>It is used in the purification of bauxite.<\/li>\n<li>It is used in manufacturing of soap, paper.<\/li>\n<li>It is used in manufacturing of antificial silk.<\/li>\n<li>It is used in manufacturing of so many chemically.<\/li>\n<li>It is used in textile industries for mercerising cotton fabrics.<\/li>\n<li>It is used in preparation of pure fats and oils.<\/li>\n<li>It is used in as laboratory reagent.<\/li>\n<\/ul>\n<p>Question 23.<br \/>\nDescribe the important uses of sodium carbonate.<br \/>\nAnswer:<br \/>\nUses:<\/p>\n<ul>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in the manufacturing of glass.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in the manufactuing of borax, caustic soda.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in paper, paints and textile industries.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in softening of water.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in laundries.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used an important laboratory reagent both in qualitative and quantitative analysis.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 24.<br \/>\nDescribe the important uses of quick line.<br \/>\nAnswer:<br \/>\nUses:<\/p>\n<ul>\n<li>Quick lime is used in the purification of sugar.<\/li>\n<li>Quick lime is used in the manufacture of dyestuffs.<\/li>\n<li>Quick lime is used in the manufacture of Na<sub>2<\/sub>CO<sub>3<\/sub> from NaOH.<\/li>\n<li>It is an important material for manufacturing of cement and it is the cheapest form of alkali.<\/li>\n<\/ul>\n<p>Question 25.<br \/>\nDraw the structures of<\/p>\n<ol>\n<li>BeCl<sub>2<\/sub> (vapour) and<\/li>\n<li>BeCl<sub>2<\/sub> (Solid).<\/li>\n<\/ol>\n<p>Answer:<\/p>\n<ol>\n<li>In vapour phase BeCl<sub>2<\/sub> forms a bridged dimer which disociates into monomer at high temperatures (around 1200 k)<br \/>\nCl &#8211; Be &#8211; Cl<\/li>\n<li>In solid state BeCl<sub>2<\/sub> has a chain structure.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24698\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-1.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 1\" width=\"459\" height=\"79\" \/><\/li>\n<\/ol>\n<p>Question 26.<br \/>\nDescribe the importance of Plaster of Paris.<br \/>\nAnswer:<\/p>\n<ol>\n<li>Plaster of paris has an important property of setting with water.<\/li>\n<li>It forms a hard solid in 5 to 15 min. When it is mixed with suitable quantity of water.<\/li>\n<li>It is majorly used in building industry and as well as plasters.<\/li>\n<li>It is used in the bone fractures (or) sprain conditions.<\/li>\n<li>It is used in dentistry.<\/li>\n<li>It is used in manufacturing status and busts.<\/li>\n<\/ol>\n<p>Question 27.<br \/>\nWhich of the alkaline earth metal carbonates is thermally the most stable ? Why ?<br \/>\nAnswer:<br \/>\nAmong Alkaline earth metal carbonates BaCO<sub>3<\/sub> is thermally most stable.<br \/>\nReason :<br \/>\nAs the cationic size increases thermal stability also increases. So BaCO<sub>3<\/sub> is most stable thermally.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 28.<br \/>\nWrite balanced equations for the reactions between<\/p>\n<ol>\n<li>Na<sub>2<\/sub>O<sub>2<\/sub> and water<\/li>\n<li>K<sub>2<\/sub>O and water.<\/li>\n<\/ol>\n<p>Answer:<\/p>\n<ol>\n<li>Na<sub>2<\/sub>O<sub>2<\/sub> + 2H<sub>2<\/sub>O \u2192 2 NaOH + H<sub>2<\/sub>O<sub>2<\/sub><\/li>\n<li>K<sub>2<\/sub>O + H<sub>2<\/sub>O \u2192 2 KOH.<\/li>\n<\/ol>\n<p><span style=\"color: #0000ff;\">Short Answer Questions<\/span><\/p>\n<p>Question 1.<br \/>\nAlkali metals and their salts impart characteristic colours to an oxidizing flame. Explain the resonizing flame. Explain the reason.<br \/>\nAnswer:<br \/>\nAlkali metals and their salts impart characterstic colours to an oxidizing flame.<\/p>\n<p>Reasons :<br \/>\nThe heat from the flame excites the outer most orbital electron to a higher energy level. When the excited electron emitts the radiation and comes back to the ground state. This falls in the visible region.<\/p>\n<p>Question 2.<br \/>\nWhat makes caesium and potassium useful as electrodes in photoelectric cells ?<br \/>\nAnswer:<\/p>\n<ul>\n<li>Alkali metals can be detected by the respective flame tests and can be determined by the flame photo metry (or) atomic absorption spectroscopy.<\/li>\n<li>Alkali metals when irradiated with light, the light energy absorbed may be sufficient to make an atom lose electron.<\/li>\n<li>This makes caesium and potassium useful as electrodes in photo electric cells.<\/li>\n<\/ul>\n<p>Question 3.<br \/>\nWrite a short note on the reactivity of alkali metals towards air.<br \/>\nAnswer:<\/p>\n<ul>\n<li>The alkali metals forms their oxides in presence of dry air and tarnished.<\/li>\n<li>These oxides reacts with moisture to form hydroxides.<\/li>\n<li>They burn vigorously in oxygen and forms oxides.\n<ul>\n<li>Lithium forms Lithium monoxide.<\/li>\n<li>Sodium forms monoxide with limited supply of oxygen and peroxide with excess of oxygen.<\/li>\n<li>Other metals of this group forms super oxides. The super oxide ion (O<sub>2<\/sub><sup>&#8211;<\/sup>) is stable only in presence of large cations.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>Reactions :<br \/>\n4Li + O<sub>2<\/sub> \u2192 2 Li<sub>2<\/sub>O<br \/>\n4Na + O<sub>2<\/sub> (Limited) \u2192 2 Na<sub>2<\/sub>O<sub>2<\/sub><br \/>\n2Na + O<sub>2<\/sub> (Excess) \u2192 Na<sub>2<\/sub>O<sub>2<\/sub><br \/>\nK + O<sub>2<\/sub> (Excess) \u2192 KO<sub>2<\/sub><br \/>\nLithium shows a different character. It reacts directly with nitrogen of air and forms Li<sub>3<\/sub>N (Lithium nitride).<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 4.<br \/>\nGive any two uses for each of the following metals.<\/p>\n<ol>\n<li>Lithium<\/li>\n<li>Sodium.<\/li>\n<\/ol>\n<p>Answer:<\/p>\n<ol>\n<li>Uses of Lithium : &#8211;<\/li>\n<\/ol>\n<ul>\n<li>&#8216;Li&#8217; metal is used to make alloys.<br \/>\nEg: 1) Lithium with lead forms an alloy which is used for making white metal bearings for motor engines.<br \/>\n2) Lithium with aluminium forms alloys which are used to make air craft parts.<\/li>\n<li>&#8216;Li&#8217; metal is used in thermo nuclear reactions.<\/li>\n<li>&#8216;Li&#8217; metal is used to make electro chemical cells.<\/li>\n<\/ul>\n<p>2) Uses of sodium : &#8211;<\/p>\n<ul>\n<li>Sodium metal is used to make Na and Pb alloy needed to make TEL. this TEL (tetra ethyl lead) is used as antiknock additives to petrol.<\/li>\n<li>Liquid &#8216;Na&#8217; metal is used as a coolant in fast breeder nuclear reactors.<\/li>\n<li>&#8216;Na&#8217; metal is used in the manufacturing of rabber.<\/li>\n<\/ul>\n<p>Question 5.<br \/>\nGive an account of properties of washing soda.<br \/>\nAnswer:<br \/>\nProperties of washing soda : &#8211;<\/p>\n<ul>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is a white crystalline solid.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> exists as a decahydrate Na<sub>2<\/sub>CO<sub>3<\/sub>. 10H<sub>2<\/sub>O which is called washing soda.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is readily soluble in water.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> (deca hydrate) when heated it loses the water molecules and forms monohydrate. This monohydrate on heating above 373 K it forms anhydrous form which is called soda ash, a white powder.<br \/>\nReactions : &#8211;<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24699\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-2.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 2\" width=\"471\" height=\"108\" \/><\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> (aq) solution is alkaline (basic) in nature Because it under goes anionic hydrolysis. (PH &gt; 7).<br \/>\nCO<sub>3<\/sub><sup>-2<\/sup> + H<sub>2<\/sub>O \u2192 HCO<sub>3<\/sub><sup>&#8211;<\/sup> + OH<sup>&#8211;<\/sup><\/li>\n<\/ul>\n<p>Question 6.<br \/>\nMention some uses of sodium carbonate.<br \/>\nAnswer:<br \/>\nUses :<\/p>\n<ul>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in the manufacturing of glass.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in the manufacturing of borax, caustic soda.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in paper, paints and textile industries. .<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in softening of water.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in laundries.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used an important laboratory reagent both in qualitative and quantitative analysis.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 7.<br \/>\nHow do you obtain pure sodium chloride from a crude sample ?<br \/>\nAnswer:<\/p>\n<ol>\n<li>Crude sodium chloride is obtained by the crystallisation of brine solution.<\/li>\n<li>Crude sodium chloride contains sodium sulphate, calcium sulphate, calcium chloride and magnesium chloride.<\/li>\n<li>CaCl<sub>2<\/sub> and MgCl<sub>2<\/sub> are the impurities in the Crude NaCl because these absorb moisture easily from the atmosphere.<\/li>\n<li>Pure sodium chloride&#8217;s obtained by dissolving Crude NaCl in minimum amount of water and filtered to remove insoluble impurities.<\/li>\n<li>This solution is saturated with HCl gas. Then crystals of pure NaCl are separated out.<\/li>\n<li>Ca and Mg chloride are more soluble in solution than NaCl and these remained in the solution.<\/li>\n<\/ol>\n<p>Question 8.<br \/>\nWhat do you know about Castner &#8211; Kellner process ? Write the principle involved in it.<br \/>\nAnswer:<\/p>\n<ul>\n<li>Castner &#8211; Kellner process is a commercial method used for the preparation of sodium hydroxide.<\/li>\n<li>In this process sodium hydroxide is prepared by the electrolysis of sodium chloride in Castner &#8211; Kellner cell.<\/li>\n<li>Brine solution is electrolysed using a mercury cathode and a carbon anode.<\/li>\n<li>Sodium metal is formed at cathode and it combine with mercury to form sodium amalgam. Chlorine gas is evolved at anode.<\/li>\n<li>The amalgam is treated with water to form, sodium hydroxide.<br \/>\nCell Reactions :<br \/>\n2NaCl \u2192 2Na<sup>+<\/sup> + 2Cl<sup>&#8211;<\/sup><br \/>\n2Na<sup>+<\/sup> + 2e<sup>&#8211;<\/sup> <img loading=\"lazy\" class=\"alignnone size-full wp-image-24700\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-3.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 3\" width=\"58\" height=\"27\" \/> 2Na &#8211; amalgam<br \/>\n2Cl<sup>&#8211;<\/sup> \u2192 Cl<sub>2<\/sub> + 2e<sup>&#8211;<\/sup><br \/>\n2Na &#8211; amalgam + 2H<sub>2<\/sub>O \u2192 2NaOH + 2Hg + H<sub>2<\/sub><\/li>\n<li>This process is also called as mercury cathode process.<\/li>\n<\/ul>\n<p>Question 9.<br \/>\nWrite a few applications of caustic soda.<br \/>\nAnswer:<br \/>\nUses :<\/p>\n<ul>\n<li>It is used in petrol refining<\/li>\n<li>It is used in the purification of bauxite.<\/li>\n<li>It is used in manufacturing of soap, paper.<\/li>\n<li>It is used in manufacturing of antificial silk.<\/li>\n<li>It is used in manufacturing of so many chemically.<\/li>\n<li>It is used in textile industries for mercerising cotton fabrics.<\/li>\n<li>It is used in preparation of pure fats and oils.<\/li>\n<li>It is used in as laboratory reagent.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 10.<br \/>\nGive an account of the biological importance of Na<sup>+<\/sup> and K<sup>+<\/sup> ions.<br \/>\nAnswer:<\/p>\n<ul>\n<li>Na<sup>+<\/sup> ions participate in the transmission of nerve signals.<\/li>\n<li>Na<sup>+<\/sup> ions regulates the flow of water accross cell membranes.<\/li>\n<li>Na<sup>+<\/sup> ions responsible for transport of sugars and amino acids into cells.<\/li>\n<li>K<sup>+<\/sup> ions are useful in activating enzymes.<\/li>\n<li>K<sup>+<\/sup> ions participate in the oxidation of glucose to produce ATP.<\/li>\n<li>K<sup>+<\/sup> along with Na+ responsible for the transmission of nerve signals.<\/li>\n<\/ul>\n<p>Question 11.<br \/>\nMention the important uses of Mg metal.<br \/>\nAnswer:<\/p>\n<ol>\n<li>Magnesium forms so many useful alloys with Al, Zn, Mn and Sn.<\/li>\n<li>Mg &#8211; Al alloys are useful in air &#8211; craft construction.<\/li>\n<li>Mg powder and ribbon is used in flash powders bulbs.<\/li>\n<li>Mg is used in incendiary bombs and signals.<\/li>\n<li>Milk of magnesice is used as antacid in medicine.<\/li>\n<li>MgCO<sub>3<\/sub> is the main ingradient in tooth pastes.<\/li>\n<\/ol>\n<p>Question 12.<br \/>\nShow that Be(OH)<sub>2<\/sub> is amphoteric in nature.<br \/>\nAnswer:<\/p>\n<ol>\n<li>Be(OH)<sub>2<\/sub> is amphoteric in nature. This can be evidented by the following reactions.<\/li>\n<li>Be(OH)<sub>2<\/sub> reacts with both acids and alkalis.<br \/>\nBe(OH)<sub>2<\/sub> + 2OH<sup>&#8211;<\/sup> [Be(OH)<sub>4<\/sub>]<sup>2-<\/sup> (Beryllation)<br \/>\nBe(OH)<sub>2<\/sub> + 2HCl + 2H<sub>2<\/sub>O \u2192 [Be(OH)<sub>4<\/sub>]Cl<sub>2<\/sub><\/li>\n<li>Hence Be(OH)<sub>2<\/sub> is amphoteric in nature.<\/li>\n<\/ol>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 13.<br \/>\nWrite a note on anomalous behaviour of beryllium.<br \/>\nAnswer:<br \/>\nAnomalous characters of Be:<br \/>\nAs was already discussed in the earlier sections, the first element shows some differences from the properties of the other elements in the group. Be differs from the other alkaline earth metals because of its small size and high electronegativity. Be differs from the other elements in the following aspects.<\/p>\n<ol>\n<li>Be compounds are predominantly covalent due to its high polarizing power and its salts are readily Hydrolyzed.<\/li>\n<li>Be is not easily affected by dry air and does not decompose water at ordinary temperature.<\/li>\n<li>Be is an amphoteric metal. It dissolves in alkali solutions forming beryllates.<\/li>\n<li>Be SO<sub>4<\/sub> is soluble in water whereas the sulphates of Ca, Sr and Ba are not soluble.<\/li>\n<li>Be and its salts do not respond to flame test while Ca, Sr and Ba give characteristic flame colours.<\/li>\n<li>Be forms many complexes while the heavier elements do not show a great tendency to form complexes.<\/li>\n<li>Be has a maximum covalency of 4 while other can have a maximum covalency of 6.<\/li>\n<\/ol>\n<p>Question 14.<br \/>\nBe shows diagonal relationship with Al. Discuss.<br \/>\nAnswer:<\/p>\n<ol>\n<li>&#8216;Be&#8217; shows diagonal relation ship with &#8216;Al&#8217;.<\/li>\n<li>The ionic radius of Be<sup>+2<\/sup> is nearly same as that of Al<sup>+3<\/sup> so &#8216;Be&#8217; resembles &#8216;Al&#8217; in several ways.<\/li>\n<li>Al, Be both not readily reacts with acids. This is due to the presence of an oxide film on the surface of metal.<\/li>\n<li>Al(OH)<sub>3<\/sub>, Be(OH)<sub>2<\/sub> both similarly dissolves in excess of alkali and forms Beryllate ion [Be(OH)<sub>3<\/sub>]<sup>2-<\/sup> and Aluminate [Al(OH)<sub>4<\/sub>] ions respectively.<\/li>\n<li>The chlorides of Be, Al have bridged chloride structures in vapour phase.<\/li>\n<li>Both the chlorides of Be, Al used as strong Lewis acids.<\/li>\n<li>Both the chlorides of Be, Al used in Friedal craft catalysts.<\/li>\n<li>Be, Al ions have strong tendency to form complexes.<\/li>\n<\/ol>\n<p>Question 15.<br \/>\nWhat is Plaster of Paris ? Write a short note on it. [T.S. Mar. 16]<br \/>\nAnswer:<br \/>\nPlaster of paris is the hemi hydrate of CaSO<sub>4<\/sub> with formula CaSO<sub>4<\/sub>. \\(\\frac{1}{2}\\)H<sub>2<\/sub>O.<br \/>\nPreparation: &#8211;<br \/>\nPlaster of paris is obtained by heating gypsum at 393 K.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24701\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-4.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 4\" width=\"364\" height=\"32\" \/><\/p>\n<ol>\n<li>If temperature is used greater than 393 K then an hydrous CaSO<sub>4<\/sub> is formed which is called &#8216;dead burnt plaster&#8217;.<\/li>\n<li>Plaster of paris has an important property of setting with water.<\/li>\n<li>It forms a hard solid in 5 to 15 min. when it is mixed with suitable quantity of water.<\/li>\n<li>It is majorly used in building industry and as well as plasters.<\/li>\n<li>It is used in the bone fractures (or) sprain conditions.<\/li>\n<li>It is used in dentistry.<\/li>\n<li>It is used in manufacturing status and busts.<\/li>\n<\/ol>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 16.<br \/>\nIn what ways lithium shows similarities to magnesium in its chemical behaviour ?<br \/>\nAnswer:<br \/>\nDiagonal relationship of Li : In the periodic table an element of a group in the 2<sup>nd<\/sup> period shows similar properties with the second element of the next group in the third period. This relation is known as diagonal relationship. For examples. Lithium and Magnesium show diagonal relationship. The elements show that diagonal relationship have similar polarizing powers, electronegativities, nature of the compounds. The diagonal similarity may be due to the effects of size and charge. For example, charge per unit area.<br \/>\nLithium shows similarity to Magnesium in the following respects.<br \/>\na) Lithium is slow to react with water. Magnesium decomposes water only in the hot condition.<br \/>\n2Li + 2H<sub>2<\/sub>O \u2192 + H<sub>2<\/sub>;<br \/>\nMg + 2H<sub>2<\/sub>O \u2192 Mg(OH)<sub>2<\/sub> + H<sub>2<\/sub><\/p>\n<p>b) Lithium combines directly with N2 forming nitride.<br \/>\n6Li + N<sub>2<\/sub> \u2192 2Li<sub>3<\/sub>N<\/p>\n<p>c) Both Lithium and Magnesium give only monoxides Li<sub>2<\/sub>O, MgO.<\/p>\n<p>d) Lithium chloride is deliquescent like MgCl<sub>2<\/sub>, LiCl undergoes hydrolysis to a smaller extent in hot water in a similar way to MgCl<sub>2<\/sub>.<\/p>\n<p>e) Due to their covalent nature, the halides Lithium and Magnesium are soluble in organic solvents.<\/p>\n<p>f) Both Li<sup>+<\/sup> and Mg<sup>+2<\/sup> are highly hydrated.<\/p>\n<p>g) The Carbonates, Phosphates and Fluorides of both Li and Mg are sparingly soluble in water.<\/p>\n<p>h) Lithium alkyls (Li<sup>+<\/sup> R<sup>&#8211;<\/sup>) are chemically similar to Grignard reagents in organic synthesis.<\/p>\n<p>Question 17.<br \/>\nWhen an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change.<br \/>\nAnswer:<\/p>\n<ul>\n<li>The alkali metals dissolve in liquid NH3 and gives deep blue solutions. These are conducting in nature.<\/li>\n<li>The blue colour of the solution is due to the ammoniated electrons which absorbs energy in the visible region of light and thus imparts blue colour to the solution.<\/li>\n<li>These solutions are paramagnetic and on standing liberate hydrogen resulting in the formation of amide.<br \/>\nM + (x + y) NH<sub>3<\/sub> \u2192 [M(NH<sub>3<\/sub>)<sub>x<\/sub>]<sup>+<\/sup> + [e(NH<sub>3<\/sub>)<sub>y<\/sub>]<sup>&#8211;<\/sup><br \/>\nM<sub>(am)<\/sub><sup>+<\/sup> + e<sup>&#8211;<\/sup> + NH<sub>3<\/sub> \u2192 MNH<sub>2(am)<\/sub> + 1\/2 H<sub>2(g)<\/sub><\/li>\n<li>In concentrated solution the blue colour Changes to bronze.colour on warming and becomes did magnetic.<\/li>\n<\/ul>\n<p>Question 18.<br \/>\nWhat happens when<\/p>\n<ol>\n<li>Sodium metal is dropped in water ?<\/li>\n<li>Sodium metal is heated in a free supply of air ?<\/li>\n<li>Sodium peroxide dissolves in water ?<\/li>\n<\/ol>\n<p>Answer:<\/p>\n<ol>\n<li>Sodium metal when dropped in water it reacts with water vigourously and liberates H<sub>2<\/sub> gas.<br \/>\n2Na + 2H<sub>2<\/sub>O \u2192 2NaOH + H<sub>2<\/sub><\/li>\n<li>Sodium metal is heated in free supply of air to form sodium peroxide.<br \/>\n2Na + O<sub>2<\/sub> \u2192 Na<sub>2<\/sub>O<sub>2<\/sub> (sodium peroxide)<\/li>\n<li>Sodium peroxide dissolves in water and forms NaOH and hydrogen peroxide.<br \/>\nNa<sub>2<\/sub>O<sub>2<\/sub> + 2H<sub>2<\/sub>O \u2192 2NaOH + H<sub>2<\/sub>O<sub>2<\/sub><\/li>\n<\/ol>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 19.<br \/>\nStates as to why<br \/>\ni) An aqueous solution of Na<sub>2<\/sub>CO<sub>3<\/sub><sup>&#8211;<\/sup> is alkaline ;<br \/>\nii) Alkali metals are prepared by the electrolysis of their fused chlorides ?<br \/>\nAnswer:<br \/>\ni) An aqueous solution of Na<sub>2<\/sub>CO<sub>3<\/sub> is alkaline. This is due to anionic (CO<sub>3<\/sub><sup>-2<\/sup>) hydrolysis.<br \/>\nCO<sub>3<\/sub><sup>-2<\/sup> + H<sub>2<\/sub>O \u2192 HCO<sub>3<\/sub><sup>-2<\/sup> + OH<sup>&#8211;<\/sup><br \/>\n\u2234 PH &gt; 7. So the solution is alkaline in nature.<\/p>\n<p>ii) Chemically alkali metals are highly reactive and they are placed at top in the electro chemical series.<br \/>\n\u2234 Common methods of extraction of the metals are not applicable for the alkali metals. So electrolytic reduction of their used chlorides is the possible method for extracting alkali metals.<br \/>\nEg: &#8216;Na&#8217; metal obtained from fused &#8216;NaCl&#8217;.<\/p>\n<p>Question 20.<br \/>\nHow would you explain the following observations ?<\/p>\n<ol>\n<li>BeO is almost insoluble but BeSO<sub>4<\/sub> is soluble in water ?<\/li>\n<li>BaO is soluble but BaSO<sub>4<\/sub> is insoluble in water ?<\/li>\n<\/ol>\n<p>Answer:<\/p>\n<ol>\n<li>BeO has amphoteric nature and the solubility in water is low because of its covalent nature.<br \/>\nBeSO<sub>4<\/sub> is soluble in water. This is due to greater hydration energy of Be<sup>+2<\/sup> ion.<\/li>\n<li>BaO is soluble in water because of its ionic nature.<br \/>\nBaSO<sub>4<\/sub> is insoluble in water because of low hydration energy of Ba<sup>+2<\/sup> ion.<\/li>\n<\/ol>\n<p><span style=\"color: #0000ff;\">Long Answer Questions<\/span><\/p>\n<p>Question 1.<br \/>\nJustify the inclusion of alkali metals in the same group of the periodic table with reference to the following :<br \/>\ni) Electronic configuration<br \/>\nii) Reducing nature<br \/>\niii) Oxides and hydroxides.<br \/>\nAnswer:<br \/>\ni) Electronic configuration : All the alkali metals have one valence electron, ns<sup>1<\/sup>.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24702\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-5.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 5\" width=\"703\" height=\"187\" \/><br \/>\nii) Reducing nature :<\/p>\n<ul>\n<li>Alkali metals are strong reducing agents.<\/li>\n<li>&#8216;Li&#8217; is most powerful reducing agent and &#8216;Na&#8217; is poor reducing agent. .<br \/>\nThe standard electrode potential (E\u00b0) is the measure of reducing power.<\/li>\n<li>&#8216;Li&#8217; has highest hydration enthalpy. It has high negative S.E.P. (E\u00b0) hence it has high reducing power.<\/li>\n<\/ul>\n<p>iii) Oxides and hydroxides : &#8211;<\/p>\n<ul>\n<li>The alkali metals forms their oxides in presence of dry air and tarnished.<\/li>\n<li>These oxides reacts with , .noisture to form hydroxides.<\/li>\n<li>They burn vigorously in oxygen and forms oxides.\n<ol>\n<li>Lithium forms lithium monoxide.<\/li>\n<li>Sodium forms monoxide with limited supply of oxygen and peroxide with&#8217; excess of oxygen<\/li>\n<li>Other metals of this group forms super oxides. The super oxide ion (O<sub>2<\/sub><sup>&#8211;<\/sup>) is stable only in presence of large cations.<\/li>\n<\/ol>\n<\/li>\n<\/ul>\n<p>Reactions:<br \/>\n4Li + O<sub>2<\/sub> \u2192 2 Li<sub>2<\/sub>O<br \/>\n4Na + O<sub>2<\/sub> (Limited) \u2192 2 Na<sub>2<\/sub>O<br \/>\n2 Na + O<sub>2<\/sub> (Excess) \u2192 Na<sub>2<\/sub>O<sub>2<\/sub><br \/>\nK + O<sub>2<\/sub> (Excess) \u2192 KO<sub>2<\/sub><br \/>\nLithium shows a different character. It reacts directly with nitrogen of air and forms Li<sub>3<\/sub>N (Lithium nitride).<\/p>\n<ul>\n<li>Alkali metal oxides easily hydrolysed by water to form the hydroxides.<br \/>\nMonoxide : M<sub>2<\/sub>O + H<sub>2<\/sub>O \u2192 2MOH<br \/>\nPeroxide : M<sub>2<\/sub>O<sub>2<\/sub> + 2H<sub>2<\/sub>O \u2192 2MOH + H<sub>2<\/sub>O<sub>2<\/sub><br \/>\nSuperoxide : 2MO<sub>2<\/sub> + 2H<sub>2<\/sub>O \u2192 2MOH + H<sub>2<\/sub>O<sub>2<\/sub> + O<sub>2<\/sub><\/li>\n<li>Oxides, peroxides are colourless whereas superoxides are coloured because of their para mag-netic property.<\/li>\n<li>Hydroxides are white crystalline solids.<\/li>\n<li>Hydroxides are strong bases and dissolved freely in water and evolve much heat.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 2.<br \/>\nWrite an essay on the differences between lithium and other alkali metals.<br \/>\nAnswer:<br \/>\nAnomalous properties of Lithium : In the periodic table some representative elements of different series show similarities, known as diagonal relationship. Li, of the alkali metals, show such a similarity with Mg of II group. That means it differs from alkali metals. Some of the important abnormal characters of lithium are given below.<br \/>\na) Lithium is hard metal while other alkali metals are soft and can be cut with the knife. Its melting point and boiling point are high.<\/p>\n<p>b) Lithium directly unites with N<sub>2<\/sub> while no other alkali metal combines directly.<br \/>\n6Li + N<sub>2<\/sub> \u2192 2Li<sub>3<\/sub>N<\/p>\n<p>c) Lithium element forms a carbide on direct combination. Group IA elements do not form directly. But all these elements are known to give carbides.<\/p>\n<p>d) The solubilities of Lithium Hydroxide (LiOH), Lithium Carbonate (Li<sub>2<\/sub>CO<sub>3<\/sub>), Lithium Phosphate (Li<sub>3<\/sub>PO<sub>4<\/sub>) and Lithium Fluoride (LiF), are very less compared to the high solubilities of the other alkali metal compounds.<\/p>\n<p>e) Lithium Hydroxide is a weaker alkali than the alkali metal Hydroxides. Basic nature of other alkali metal Hydroxides is more than Li(OH). Because of this Lithium Hydroxide Carbonate, nitrates are thermally unstable.<\/p>\n<p>Question 3.<br \/>\nDiscuss the preparation and properties of sodium carbonate.<br \/>\nAnswer:<br \/>\nPreparation :<\/p>\n<ul>\n<li>Sodium carbonate is prepared by solvay process.<\/li>\n<li>In this process sodium chloride reacts with ammonium bicarbonate and gets precipitated the low soluble sodium bicarbonate.<\/li>\n<li>The lather is prepared by passing CO<sub>2<\/sub> into a concentrated solution of NaCl saturated with ammonia. Here (NH<sub>4<\/sub>)<sub>2<\/sub>CO<sub>3<\/sub> followed by NH<sub>4<\/sub> HCO<sub>3<\/sub> are formed.<br \/>\nChemical equations involved :<br \/>\n2NH<sub>3<\/sub> + H<sub>2<\/sub>O + CO<sub>2<\/sub> \u2192 (NH<sub>4<\/sub>)<sub>2<\/sub> CO<sub>3<\/sub><br \/>\n(NH<sub>4<\/sub>)<sub>2<\/sub> CO<sub>3<\/sub> + H<sub>2<\/sub>O + CO<sub>2<\/sub> \u2192 2NH<sub>4<\/sub>HCO<sub>3<\/sub><br \/>\nNH<sub>4<\/sub>HCO<sub>3<\/sub> + NaCl \u2192 NH<sub>4<\/sub>Cl + NaHCO<sub>3<\/sub><\/li>\n<li>The separated NaHC03 Crystals heated to get Na<sub>2<\/sub>CO<sub>3<\/sub>.<br \/>\n2NaHCO<sub>3<\/sub> \u2192 Na<sub>2<\/sub>CO<sub>3<\/sub> + H<sub>2<\/sub>O + CO<sub>2<\/sub><\/li>\n<li>In this process ammonia is regenerated by Ca(OH)<sub>2<\/sub>.<br \/>\n2NH<sub>4<\/sub>Cl + Ca(OH)<sub>2<\/sub> \u2192 2NH<sub>3<\/sub> + CaCl<sub>2<\/sub> + H<sub>2<\/sub>O<\/li>\n<\/ul>\n<p>Properties of washing soda :<\/p>\n<ul>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is a white crystalline solid.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> exists as a decahydrate Na<sub>2<\/sub>CO<sub>3<\/sub>. 10H<sub>2<\/sub>O which is called washing soda.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is readily soluble in water.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> (decahydrate) when heated it loses the water molecules and forms monohydrate. This monohydrate on heating above 373 K it forms anhydrous form which is called soda ash, a white powder.<br \/>\nReactions : &#8211;<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24699\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-2.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 2\" width=\"471\" height=\"108\" \/><\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> (aq) solution is alkaline (basic) in nature Because it under goes anionic hydrolysis. (PH &gt; 7).<br \/>\nCO<sub>3<\/sub><sup>-2<\/sup> + H<sub>2<\/sub>O \u2192 HCO<sub>3<\/sub><sup>&#8211;<\/sup> + OH<sup>&#8211;<\/sup><\/li>\n<\/ul>\n<p>Uses :<\/p>\n<ul>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in the manufactuing of glass.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in the manufactuing of borax, caustic soda.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in paper, paints and textile industries.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in softening of water.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used in laundries.<\/li>\n<li>Na<sub>2<\/sub>CO<sub>3<\/sub> is used an important laboratory reagent both in qualitative and quantitative analysis.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 4.<br \/>\nDiscuss the similarities between alkaline earth metals and gradation in the following aspects.<br \/>\ni) Electronic configuration<br \/>\nii) Hydration enthalpies<br \/>\niii) Nature of oxides and hydroxides.<br \/>\nAnswer:<br \/>\ni) Electronic configuration :<br \/>\nThe general electronic configuration of alkaline earth metals represented by [noble gas] ns<sup>2<\/sup>.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24703\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-6.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 6\" width=\"662\" height=\"228\" \/><\/p>\n<p>ii) Hydration Enthalpies :<\/p>\n<ul>\n<li>The hydration enthalpies of alkaline earth metal ions decrease with increase in ionic size down the group.<br \/>\nBe<sup>+2<\/sup> &gt; Mg<sup>+2<\/sup> &gt; Ca<sup>+2<\/sup> &gt; Sr<sup>+2<\/sup> &gt; Ba<sup>+2<\/sup><\/li>\n<li>Hydration enthalpies of these elements ions are larger than those of alkali metal ions.<br \/>\nEg : MgCl<sub>2<\/sub> MgCl<sub>2<\/sub> . 6H<sub>2<\/sub>O<br \/>\nCaCl<sub>2<\/sub> CaCl<sub>2<\/sub> . 6H<sub>2<\/sub>O<\/li>\n<\/ul>\n<p>iii) Nature of oxides and hydroxides : &#8211;<\/p>\n<ul>\n<li>Alkaline earth metals forms oxides of type MO.<\/li>\n<li>These are formed by burning in oxygen.<\/li>\n<li>BeO is amphoteric and covalent in nature whereas other oxides are ionic and basic in nature. Other oxides i.e., except BeO forms hydroxides with water.<br \/>\nEg : MgO + H<sub>2<\/sub>O \u2192 Mg(OH)<sub>2<\/sub><\/li>\n<li>The solubility, thermal stability and the basic character of these hydroxides increase with increase of atomic no. from Mg(OH)<sub>2<\/sub> to Ba(OH)<sub>2<\/sub>. H<\/li>\n<li>These hydroxides are less basic, less stable than alkali metal hydroxide.<\/li>\n<li>Be(OH)<sub>2<\/sub> is amphoteric in nature. This can be evidented by the following reactions.<\/li>\n<li>Be(OH)<sub>2<\/sub> reacts with both acids and alkalis.<br \/>\nBe(OH)<sub>2<\/sub> + 2OH<sup>&#8211;<\/sup> [Be(OH)<sub>4<\/sub>]<sup>2-<\/sup> (Beryllation)<br \/>\nBe(OH)<sub>2<\/sub> + 2HCl + 2H<sub>2<\/sub>O \u2192 [Be(OH)<sub>4<\/sub>]Cl<sub>2<\/sub><\/li>\n<li>Hence Be(OH)<sub>2<\/sub> is amphoteric in nature.<\/li>\n<\/ul>\n<p>Question 5.<br \/>\nDiscuss on;<br \/>\ni) Carbonates<br \/>\nii) Sulphates and<br \/>\niii) Nitrates of alkaline earth metals.<br \/>\nAnswer:<br \/>\ni) Carbonates :<\/p>\n<ul>\n<li>Alkaline earth metals forms MCO<sub>3<\/sub> type carbonates.<\/li>\n<li>These Carbonates are insoluble in water.<\/li>\n<li>The solubility of these carbonates in water decreases as the atomic no.of the element increases.<\/li>\n<li>\u00a0The thermal stability increases with increasing cationic size.<\/li>\n<li>These carbonates decompose on heating to give CO<sub>2<\/sub><br \/>\nCaCO<sub>3<\/sub> <img loading=\"lazy\" class=\"alignnone size-full wp-image-24704\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-7.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 7\" width=\"47\" height=\"20\" \/> Cao + CO<sub>2<\/sub><\/li>\n<li>BeCO<sub>3<\/sub> is unstable and kept only in at atmosphere of CO<sub>2<\/sub>.<\/li>\n<\/ul>\n<p>ii) Sulphates :<\/p>\n<ul>\n<li>Alkaline earth metals forms MSO<sub>4<\/sub> type sulphates.<\/li>\n<li>These are white solids and are stable to heat.<\/li>\n<li>BeSO<sub>4<\/sub> and MgSO<sub>4<\/sub> are readily soluble in water due to high hydration enthalies of Be<sup>2+<\/sup>, Mg<sup>2+<\/sup>.<\/li>\n<li>The solubility decrease from CaSO<sub>4<\/sub> to BaSO<sub>4<\/sub>.<\/li>\n<\/ul>\n<p>iii) Nitrates :<\/p>\n<ul>\n<li>Alkaline earth metals forms M(NO<sub>3<\/sub>)<sub>2<\/sub> type Nitrates.<\/li>\n<li>These are formed by the reaction of carbonates in dil.HNO<sub>3<\/sub>.<\/li>\n<li>Mg(N03)2 crystallises with six water molecules and Ba(NO<sub>3<\/sub>)<sub>2<\/sub> is an hydrous.<\/li>\n<li>All of these decompose on heating to give the respective oxides.<br \/>\n2M(NO<sub>3<\/sub>)<sub>2<\/sub> \u2192 2MO + 4NO<sub>2<\/sub> + O<sub>2<\/sub><br \/>\nM = Be, Mg, Ca, Sr, Ba.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 6.<br \/>\nWhat are the common physical and chemical features of alkali metals ?<br \/>\nAnswer:<br \/>\nPhysical features :<\/p>\n<ul>\n<li>Alkali metals are silvery white, soft and light metals.<\/li>\n<li>These elements have low density which increases down the group from Li to Cs. (one exception density of K &lt; density of Na).<\/li>\n<li>The m.pts, b.pts of alkali metals are low.<\/li>\n<li>Alkali metals and their salts impart characterstic colours to an oxidizing flame.<\/li>\n<\/ul>\n<p>Reasons :<br \/>\nThe heat from the flame excities the outer most orbital electron to a higher energy level. When the excited electron emitts the radiation and comes back to the ground state. This falls in the visible region.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24705\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-8.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 8\" width=\"611\" height=\"101\" \/><\/p>\n<ul>\n<li>Alkali metals can be detected by the respective flame tests and can be determined by the flame photo metry (or) atomic absorption spectroscopy.<\/li>\n<li>Alkali metals when irradiated with light, the light energy absorbed may be sufficient to make an atom lose electron. .<\/li>\n<li>This makes calsium and potassium useful as electrodes in photo electric cells.<\/li>\n<\/ul>\n<p>Chemical features : &#8211;<br \/>\ni) Reactivity towards Air : \u2014<\/p>\n<ul>\n<li>The alkali metals forms their oxides in presence of dry air and tarnished.<\/li>\n<li>These oxides reacts with moisture to form hydroxides.<\/li>\n<li>They burn vigorously in oxygen and forms oxides.\n<ol>\n<li>Lithium forms Lithium monoxide.<\/li>\n<li>Sodium forms monoxide with limited supply of oxygen and peroxide with excess of oxygen.<\/li>\n<li>Other metals of this group forms super oxides. The super oxide ion (O<sub>2<\/sub><sup>&#8211;<\/sup>) is stable only in presence of large cations.<\/li>\n<\/ol>\n<\/li>\n<li>Reasons :<br \/>\n4Li + O<sub>2<\/sub> \u2192 2 Li<sub>2<\/sub>O<br \/>\n4Na + O<sub>2<\/sub> (Limited) \u2192 2 Na<sub>2<\/sub>O<br \/>\n2Na + O<sub>2<\/sub> (Excess) \u2192 Na<sub>2<\/sub>O<sub>2<\/sub><br \/>\nK + O<sub>2<\/sub> (Excess) \u2192 KO<sub>2<\/sub><\/li>\n<li>Lithium shows a different character. It reacts directly with nitrogen of air and forms Li<sub>3<\/sub>N (Lithium nitride).<\/li>\n<\/ul>\n<p>ii) Reactivity with H<sub>2<\/sub>: Alkali metals react with H<sub>2<\/sub> directly at 300 &#8211; 600\u00b0 C and form hydrides. The reaction can be written as follows :<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24706\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-9.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 9\" width=\"213\" height=\"31\" \/><br \/>\nWhere M = Li, Na, K, Rb or Cs. These hydrides are ionic in nature. Their ionic nature increases with the metalic nature of alkali metals.<\/p>\n<p>iii) Reactivity with halogens : All the alkali&#8217; metals react with halogens to give the binary compounds. The chemical reactivity in the alkali metals increases with increase in atomic number.<br \/>\n2M + X<sub>2<\/sub> \u2192 2MX (where M is any alkali metal)<br \/>\nAll the metal halides are ionic compounds.<\/p>\n<p>iv) Reactivity with water : The alkali metals decompose water vigorously and liberate hydrogen gas! The chemical reactivity of these metals increases as the atomic number increases. The metal hydroxides are formed.<br \/>\n2M + 2H<sub>2<\/sub>O \u2192 2MOH + H<sub>2<\/sub><br \/>\nWhere M = any one of the alkali metals.<\/p>\n<p>ii) Reducing nature :<\/p>\n<ul>\n<li>Alkali metals are strong reducing agents.<\/li>\n<li>&#8216;Li1 is most powerful reducing agent and &#8216;Na&#8217; is poor reducing agent.<\/li>\n<li>The standard electrode potential (E\u00b0) is the measure of reducing power.<\/li>\n<li>&#8216;Li&#8217; has highest hydration enthalpy. It has high negative S.E.P. (E\u00b0) hence it has high reducing power.<\/li>\n<li>The alkali metals dissolves in liquid NH3 and gives deep blue solutions. These are conducting in nature.<\/li>\n<li>The blue colour of the solution is due to the ammoniated electrons which absorbs energy in the visible region of light and thus imparts blue colour to the solution.<\/li>\n<li>These solutions are paramagnetic and on standing Liberate hydrogen resulting in the formation of amide.<br \/>\nM + (x + y) NH<sub>3<\/sub> \u2192 [M(NH<sub>3<\/sub>)<sub>x<\/sub>]<sup>+<\/sup> + [e(NH<sub>3<\/sub>)<sub>y<\/sub>]<sup>&#8211;<\/sup><br \/>\nM<sub>(am)<\/sub><sup>+<\/sup> + e<sup>&#8211;<\/sup> + NH<sub>3<\/sub> \u2192 MNH<sub>2(am)<\/sub> + 1\/2 H<sub>2(g)<\/sub><\/li>\n<li>In concentrated solution the blue colour Changes to bronze.colour on warming and becomes did magnetic.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 7.<br \/>\nDiscuss the general characterstics and gradation in properties of alkaline earth metals.<br \/>\nAnswer:<br \/>\nThe general characterstics and gradation in properties of alkaline earth metals follows.<br \/>\ni) Oxides and hydroxides :<\/p>\n<ul>\n<li>Alkaline earth metals forms oxides of type Mo.<\/li>\n<li>These are formed by burning in oxygen.<\/li>\n<li>BeO is amphoteric and covalent in nature where as other oxides are ionic and basic in nature.<\/li>\n<li>Other oxides i.e., except Beo forms hydroxides with water.<br \/>\nEg : MgO + H<sub>2<\/sub>O \u2192 Mg(OH)<sub>2<\/sub><\/li>\n<li>The solubility, thermal stability and the basic character of these hydroxides increase with increase of atomic no. from Mg(OH)<sub>2<\/sub> to Ba(OH)<sub>2<\/sub>.<\/li>\n<li>These hydroxides are less basic, less stable than alkali metal hydroxide.<\/li>\n<li>Be(OH)<sub>2<\/sub> is amphoteric in nature. This can be evidented by the following reactions.<\/li>\n<li>Be(OH)<sub>2<\/sub> reacts with both acids and alkalis.<br \/>\nBe(OH)<sub>2<\/sub> + 2OH<sup>&#8211;<\/sup> [Be(OH)<sub>4<\/sub>]<sup>2-<\/sup> (Beryllation)<br \/>\nBe(OH)<sub>2<\/sub> + 2HCl + 2H<sub>2<\/sub>O \u2192 [Be(OH)<sub>4<\/sub>]Cl<sub>2<\/sub><\/li>\n<li>Hence Be(OH)<sub>2<\/sub> is amphoteric in nature.<\/li>\n<\/ul>\n<p>ii) Halides:-<\/p>\n<ul>\n<li>These forms MX<sub>2<\/sub> type halides.<\/li>\n<li>Except Be &#8211; halides, all other halides of these metals are ionic.<\/li>\n<li>Be &#8211; halides are covalent and soluble in organic solvents.<\/li>\n<li>In vapour phase BeCl<sub>2<\/sub> forms a bridged dimer which disociates into monomer at high temperatures (around 1200 k)<br \/>\nCl &#8211; Be &#8211; Cl<\/li>\n<li>In solid state BeCl<sub>2<\/sub> has a chain structure.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24707\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-10.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 10\" width=\"301\" height=\"77\" \/><\/li>\n<li>The tendency to form halide hydrates gradually decreases &#8211; down the group.<br \/>\nEg : MgCl<sub>2<\/sub>, 8H<sub>2<\/sub>O, CaCl<sub>2<\/sub>, 6H<sub>2<\/sub>O, BaCl<sub>2<\/sub>. 2H<sub>2<\/sub>O.<\/li>\n<li>Ca, Sr and Ba halides, dehydration can be done by heating.<\/li>\n<li>Fluorides are less soluble than the chlorides due to their high lattice energies.<\/li>\n<\/ul>\n<p>i) Carbonates :<\/p>\n<ul>\n<li>Alkaline earth metals forms MCO<sub>3<\/sub> type carbonates.<\/li>\n<li>These Carbonates are insoluble in water.<\/li>\n<li>The solubility of these carbonates in water decreases as the atomic no.of the element increases.<\/li>\n<li>The thermal stability increases with increasing cationic size.<\/li>\n<li>These carbonates decompose on heating to give CO<sub>2<\/sub><br \/>\nCaCO<sub>3<\/sub> <img loading=\"lazy\" class=\"alignnone size-full wp-image-24704\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-7.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 7\" width=\"47\" height=\"20\" \/> Cao + CO<sub>2<\/sub><\/li>\n<li>BeCO<sub>3<\/sub> is unstable and kept only in at atmosphere of CO<sub>2<\/sub>.<\/li>\n<\/ul>\n<p>ii) Sulphates:<\/p>\n<ul>\n<li>Alkaline earth metals forms MSO<sub>4<\/sub> type sulphates.<\/li>\n<li>These are white solids and are stable to heat.<\/li>\n<li>BeSO<sub>4<\/sub> and MgSO<sub>4<\/sub> are readily soluble in water due to high hydration enthalpies of Be<sup>2+<\/sup>, Mg<sup>2+<\/sup>.<\/li>\n<li>The solubility decrease from CaSO<sub>4<\/sub> to BaSO<sub>4<\/sub>.<\/li>\n<\/ul>\n<p>iii) Nitrates:<\/p>\n<ul>\n<li>Alkaline earth metals forms M(NO<sub>3<\/sub>)<sub>2<\/sub> type Nitrates.<\/li>\n<li>These are formed by the reaction of carbonates in dil.HNO<sub>3<\/sub>.<\/li>\n<li>Mg(NO<sub>3<\/sub>)<sub>2<\/sub> crystallises with six water molecules and Ba(NO<sub>3<\/sub>)<sub>2<\/sub> is an hydrous.<\/li>\n<li>All of these decompose on heating to give the respective oxides.<br \/>\n2M(NO<sub>3<\/sub>)<sub>2<\/sub> \u2192 2MO + 4NO<sub>2<\/sub> + O<sub>2<\/sub><br \/>\nM = Be, Mg, Ca, Sr, Ba.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 8.<br \/>\nDiscuss the various reactions that occur in the solvay process. [A.P. Mar. 16]<br \/>\nAnswer:<br \/>\nPreparation:<\/p>\n<ul>\n<li>Sodium carbonate is prepared by solvay process.<\/li>\n<li>In this process sodium chloride reacts with ammonium bicarbonate and gets precipitated the low soluble sodium bicarbonate. &#8216;<\/li>\n<li>The lather is prepared by passing CO<sub>2<\/sub> in to a concentrated solution of NaCl saturated with ammonia. Here (NH<sub>4<\/sub>)<sub>2<\/sub>CO<sub>3<\/sub> followed by NH<sub>4<\/sub> HCO<sub>3<\/sub> are formed.<\/li>\n<li>Chemical equations involved:<br \/>\n2NH<sub>3<\/sub> + H<sub>2<\/sub>O + CO<sub>2<\/sub> \u2192 (NH<sub>4<\/sub>)<sub>2<\/sub> CO<sub>3<\/sub><br \/>\n(NH<sub>4<\/sub>)<sub>2<\/sub> CO<sub>3<\/sub> + H<sub>2<\/sub>O + CO<sub>2<\/sub> \u2192 2NH<sub>4<\/sub>HCO<sub>3<\/sub><br \/>\nNH<sub>4<\/sub>HCO<sub>3<\/sub> + NaCl \u2192 NH<sub>4<\/sub>Cl + NaHCO<sub>3<\/sub><\/li>\n<li>The separated NaHCO<sub>3<\/sub> Crystals heated to get Na<sub>2<\/sub>CO<sub>3<\/sub>.<br \/>\n2NaHCO<sub>3<\/sub> \u2192 Na<sub>2<\/sub>CO<sub>3<\/sub> + H<sub>2<\/sub>O + CO<sub>2<\/sub><\/li>\n<li>In this process ammonia is regenerated by Ca(OH)<sub>2<\/sub>.<br \/>\n2NH<sub>4<\/sub>Cl + Ca(OH)<sub>2<\/sub> \u2192 2NH<sub>3<\/sub> + CaCl<sub>2<\/sub> + H<sub>2<\/sub>O<\/li>\n<\/ul>\n<p>Question 9.<br \/>\nStarting with sodium chloride how would you proceed to prepare<br \/>\ni) Sodium metal<br \/>\nii) Sodium hydroxide<br \/>\niii) Sodium peroxide<br \/>\niv) sodium carbonate.<br \/>\nAnswer:<br \/>\ni) Fused NaCl on electrolysis gives sodium metal.<br \/>\n2NaCl \u2192 2Na<sup>+<\/sup> + 2Cl<sup>&#8211;<\/sup><br \/>\n2Na<sup>+<\/sup> + 2e<sup>&#8211;<\/sup> \u2192 2Na (Cathode)<br \/>\n2Cl<sup>&#8211;<\/sup> \u2192 Cl<sub>2<\/sub> + 2e<sup>&#8211;<\/sup> (anode)<\/p>\n<p>ii)<\/p>\n<ul>\n<li>Castner-Kellner process is a commercial method used for the preparation of sodium hydroxide.<\/li>\n<li>In this process sodium hydroxide is prepared by the electrolysis of sodium chloride in Castner &#8211; Kellner cel..<\/li>\n<li>Brine solution is electrolysed using a mercury cathode and a carbon anode.<\/li>\n<li>Sodium metal is formed at cathode and it combine with mercury to form sodium amalgam. Chlorine gas is evolved at anode.<\/li>\n<li>The amalgam is streated with water to form sodium hydroxide.<br \/>\nCell Reactions:<br \/>\n2NaCl \u2192 2Na<sup>+<\/sup> + 2Cl<sup>&#8211;<\/sup><br \/>\n2Na<sup>+<\/sup> + 2e<sup>&#8211;<\/sup> <img loading=\"lazy\" class=\"alignnone size-full wp-image-24708\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-11.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 11\" width=\"53\" height=\"22\" \/> 2Na &#8211; amalgam<br \/>\n2Cl<sup>&#8211;<\/sup> \u2192 Cl<sub>2<\/sub> + 2e<sup>&#8211;<\/sup><br \/>\n2Na-amalgam + 2H<sub>2<\/sub>O \u2192 2NaOH + 2Hg + H<sub>2<\/sub><\/li>\n<li>This process is also called as mercury cathode process.<\/li>\n<\/ul>\n<p>iii) The obtained Na &#8211; metal reacts with excess of oxygen to form sodium peroxide.<br \/>\n2Na + O<sub>2<\/sub> \u2192 Na<sub>2<\/sub>O<sub>2<\/sub> (Sodium peroxide.)<\/p>\n<p>iv) Preparation:<\/p>\n<ol>\n<li>Sodium carbonate is prepared by solvay process.<\/li>\n<li>In this process sodium chloride reacts with ammonium bicarbonate and gets precipitated the low soluble sodium bicarbonate.<\/li>\n<li>The lather is prepared by passing CO<sub>2<\/sub> into a concentrated solution of NaCl saturated with ammonia. Here (NH<sub>4<\/sub>)<sub>2<\/sub>CO<sub>3<\/sub> followed by NH<sub>4<\/sub> HCO<sub>3<\/sub> are formed.<\/li>\n<\/ol>\n<p>Question 10.<br \/>\nWhat happens when<br \/>\ni) Magnesium is burnt in air ?<br \/>\nii) Quick lime is heated with silica<br \/>\niii) Chlorine reacts with slaked lime<br \/>\niv) calcium nitrate is strongly heated.<br \/>\nAnswer:<br \/>\ni) Magnesium burns with dazzling brilliance in air to give MgO and Mg<sub>3<\/sub>N<sub>2<\/sub>.<br \/>\n2Mg + O<sub>2<\/sub> \u21922MgO<br \/>\n3Mg + N<sub>2<\/sub> \u2192 Mg<sub>3<\/sub>N<sub>2<\/sub><\/p>\n<p>ii) Quick lime heated with silica to form calcium silicate<br \/>\nCao + SiO<sub>2<\/sub> \u2192 CaSio<sub>3<\/sub><\/p>\n<p>iii) Slaked lime reacts with chlorine gas to form bleaching powder.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-24709\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-12.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 12\" width=\"360\" height=\"53\" \/><\/p>\n<p>iv) Calcium nitrate on strong heating to form respective oxide<br \/>\n2Ca(NO<sub>3<\/sub>)<sub>2<\/sub> \u2192 2CaO + 4NO<sub>2<\/sub> + O<sub>2<\/sub>.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 11.<br \/>\nExplain the significance of sodium, potassium, magnesium and calcium in biological fluids.<br \/>\nAnswer:<br \/>\nBiological importance of Na, K.<\/p>\n<ul>\n<li>Na<sup>+<\/sup> ions participate in the transmission of nerve signals.<\/li>\n<li>Na<sup>+<\/sup> ions regulates the flow of water accross cell membranes.<\/li>\n<li>Na<sup>+<\/sup> ions responsible for transport of sugars and amino acids into cells.<\/li>\n<li>K<sup>+<\/sup> ions are useful in activating enzymes.<\/li>\n<li>K<sup>+<\/sup> ions participate in the oxidation of glucose to produce ATP.<\/li>\n<li>K<sup>+<\/sup> along with Na<sup>+<\/sup> responsible for the transmission of nerve signals.<\/li>\n<\/ul>\n<p>Biological importance of Mg and Ca :<br \/>\nRole of Mg<sup>2+<\/sup> in biology :<\/p>\n<ol>\n<li>Mg<sup>2+<\/sup> ions are concentrated in animal cells.<\/li>\n<li>Enzymes like &#8220;phosphohydrolases1 and &#8216;Phospho transferases&#8217; contain Mg<sup>2+<\/sup> ions. These enzymes participate in ATP reactions and release energy in the process. Mg<sup>2+<\/sup> forms a complex with ATP.<\/li>\n<li>Mg<sup>2+<\/sup> is a constituent of chlorophyll, the green component of plants.<\/li>\n<\/ol>\n<p>Role of Ca<sup>+2<\/sup>:<br \/>\nAbout 99% of body calcium is present in bones and teeth. It also plays important roles in neuromuscular function, interneuronal transmission, cell membrance integrity and blood coaqulation.<\/p>\n<p>The calcium concentration in plasma is regulated at about 100 mg\/Lit. It is maintained by two hormones, calcitonin and parathyroid hormone. Ca<sup>2+<\/sup> ion are necessary for muscle contraction.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 12.<br \/>\nWrite few lines about cement ?<br \/>\nAnswer:<\/p>\n<ul>\n<li>Cement is an important building material.<\/li>\n<li>It is also called portland cement.<\/li>\n<li>Cement is obtained by combining a material rich in lime, CaO with other material such as clay which contains Sio<sub>2<\/sub> along with the oxides of Al, Fe and Mg.<\/li>\n<li>Composition of port land cement is<br \/>\nCao &#8211; 50 &#8211; 60%<br \/>\nSio<sub>2<\/sub> &#8211; 20 &#8211; 25%<br \/>\nAl<sub>2<\/sub>O<sub>3<\/sub> &#8211; 5 &#8211; 10%<br \/>\nMgo &#8211; 2 &#8211; 3%<br \/>\nFe<sub>2<\/sub>O<sub>3<\/sub> &#8211; 1 &#8211; 2%<br \/>\nand SO<sub>2<\/sub> &#8211; 1 &#8211; 2%<\/li>\n<li>For a good quality of cement the ratio of SiO<sub>2<\/sub> to Al<sub>2<\/sub>O<sub>3<\/sub> is between 2.5 and 4 and the ratio of lime (Co) to the total of the oxides of SiO<sub>2<\/sub>, Al<sub>2<\/sub>O<sub>3<\/sub> and Fe<sub>2<\/sub>O<sub>3<\/sub> is as close as &#8216;2&#8217;.<\/li>\n<li>The raw materials used for the manufacture of cement are lime stone and clay.<br \/>\nClay + lime <img loading=\"lazy\" class=\"alignnone size-full wp-image-24710\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/09\/AP-Inter-1st-Year-Chemistry-Study-Material-Chapter-9-The-s-Block-Elements-13.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements 13\" width=\"59\" height=\"25\" \/> cement clinker.<\/li>\n<li>This cement clinker mixed with 2 &#8211; 3% by wt. of gypsum to form cement.<\/li>\n<li>Important ingradients in portland cement are<br \/>\nCa<sub>2<\/sub>SiO<sub>4<\/sub> &#8211; 26%, Ca<sub>3<\/sub>SiO<sub>5<\/sub> &#8211; 51 % and Ca<sub>3<\/sub>Al<sub>2<\/sub>O<sub>6<\/sub> &#8211; 11 %<\/li>\n<\/ul>\n<p>Setting of Cement: &#8211;<\/p>\n<ul>\n<li>Cement mixed with water to give a hard mass i.e setting of cement takes place.<\/li>\n<li>This is due to the hydration of molecules of the cement.<\/li>\n<li>The purpose of adding gypsum is to slow down the process of setting and to get sufficiently hardness.<\/li>\n<\/ul>\n<p>Uses:<\/p>\n<ul>\n<li>It is used in concrete and rein forced concrete.<\/li>\n<li>It is used in plastering.<\/li>\n<li>It is used in construction of bridges, dams and buildings.<\/li>\n<\/ul>\n<p><span style=\"color: #0000ff;\">Solved Problems<\/span><\/p>\n<p>Question 1.<br \/>\nWhat is the oxidation state of K in KO<sub>2<\/sub> ?<br \/>\nSolution:<br \/>\nThe superoxide species is represented as O<sub>2<\/sub><sup>&#8211;<\/sup>; since the compound is neutral, the oxidation state of potassium is +1.<\/p>\n<p>Question 2.<br \/>\nThe E<sup>\u0398<\/sup> for Cl<sub>2<\/sub> \/ Cl<sup>&#8211;<\/sup> is + 1.36, for I<sub>2<\/sub>\/I<sup>&#8211;<\/sup> is + 0.53, for Ag<sup>+<\/sup>\/Ag is + 0.79, Na<sup>+<\/sup>\/Na is &#8211; 2.71 and for Li<sup>+<\/sup>\/Li is &#8211; 3.04. Arrange the following ionic species in decreasing order of reducing strength : I<sup>&#8211;<\/sup>, Ag, Cl<sup>&#8211;<\/sup>, Li, Na<br \/>\nSolution:<br \/>\nThe order is Li &gt; Na &gt; I<sup>&#8211;<\/sup> &gt; Ag &gt; Cl<sup>&#8211;<\/sup>.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 1st Year Chemistry Study Material Chapter 9 The s-Block Elements\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 3.<br \/>\nWhy is KO<sub>2<\/sub> paramagnetic ? [T.S. Mar. 16]<br \/>\nSolution:<br \/>\nThe superoxide O<sub>2<\/sub><sup>&#8211;<\/sup> is paramagnetic because of one unpaired electron in \u03c0*2p molecular orbital.<\/p>\n<p>Question 4.<br \/>\nWhy does the solubility of alkaline earth metal hydroxides in water increases down the group ?<br \/>\nSolution:<br \/>\nAmong alkaline earth metal hydroxides, the anion being common the cationic radius will influence the lattice enthalpy. Since lattice enthalpy decreases much more than the hydration enthalpy with increasing ionic size, the solubilit y increases as we go down the group.<\/p>\n<p>Question 5.<br \/>\nWhy does the solubility of alkaline earth metal carbonates and sulphates in water decrease down the group ?<br \/>\nSolution:<br \/>\nThe size of anions being much larger compared to cations, the lattice enthalpy will remain almost constant within a particular group. Since the hydration enthalpies decrease down the group, solubility will decrease as found for alkaline earth metal carbonates and sulphates.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Andhra Pradesh BIEAP AP Inter 1st Year Chemistry Study Material 9th Lesson The s-Block Elements Textbook Questions and Answers. AP Inter 1st Year Chemistry Study Material 9th Lesson The s-Block Elements Very Short Answer Questions Question 1. Give reasons for the diagonal relationship observed in the periodic table. Answer: Diagonal relationship is due to similar &hellip;<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[15],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/posts\/35434"}],"collection":[{"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/comments?post=35434"}],"version-history":[{"count":1,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/posts\/35434\/revisions"}],"predecessor-version":[{"id":35435,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/posts\/35434\/revisions\/35435"}],"wp:attachment":[{"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/media?parent=35434"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/categories?post=35434"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/tags?post=35434"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}