Ans_Ex7 - Nielsen CHM1041 Answer to Exercise set # 7 Ionic...

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Nielsen Bhaskar/PC/1713K/A 2/05 1 CHM1041 Answer to Exercise set # 7 Ionic Equilibria I 1. By choosing the proper temperatures, both (normally a solid) and (normally a gas) are liquids. But liquid is a good conductor of electricity and liquid is not. Why is this? On the other hand, a water solution of either substance at room temperature is a good conductor. Explain why. NaC1 HC1 NaC1 NaC1 is an ionic solid at room temperature and incapable of conducting electricity as a solid. Mobile ions are required for the conduction of electric current, and the ions of solid are locked in the crystal lattice. As a liquid at higher temperatures (molten state), the ions become mobile and the conduction of current is possible. Hydrogen chloride, is a polar covalent molecule and cannot conduct electric current as a solid, pure liquid, or gas. In water solution, however, both and produce 100% ions and both conduct current. NaC1 HC1, NaC1 100% () ( ) 2 HO s +1 -1 aq NaC1 Na + C1 aq ⎯⎯⎯→ ( ) 2 3 +1 -1 2 ga HC1 + H O H O C1 + q a q 100% 2. Calculate the concentration of each of the ions in the following solutions of strong electrolytes: (a) 0.0090 M HBr ( ) ( ) 2 +1 1 ag HBr H Br ag + 100% 0.0090 M 0.0090 M (b) 24 0.0102 M Li SO 100% 2 2 4 s +1 -2 4 ag ag Li SO SO 2L i + 0.0090 M 0.0102 M (c) ( ) 63 2 0.0033 M A1 H O SO ⎡⎤ ⎣⎦ ( ) 2 2 +3 -2 s 6ag 2 AHO S O 2AHO +3 S O AA 4 0.0066 M 0.0099 M
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Nielsen Bhaskar/PC/1713K/A 2/05 2 - 2 4 a q 2 3. Show by suitable equations that the following species are bases in water: -- 1 33 2 1 , NH , HS , CH CO andO . () +1 24 3 -1 aq aq aq HS + H O NH + OH U 32 2 3 2 -1 -1 aq aq CH CO +HO CHCOH U -2 -1 -1 2 aq aq aq O + H O OH OH + 4. Show by suitable equations that the following species are acids in water: +1 ,. HBr , HNO HBrO , and PH ( ) 2 +1 -1 3 ga q HBr H O H O Br ++ 23 +1 -1 2aq aq HNO + H O H O + NO U 4 +1 -1 4aq HBrO + BrO HO +1 +1 42 3 aq aq 3 aq PH + H O H O + PH U 5. Substances that exhibit both acidic and basic properties are said to be “amphoteric.” The existence of such substances is rather easily understood in terms of Bronsted-Lowry theory. Which of the following is amphoteric? (Hint: Which can either gain or lose protons?) -1 (a) OH 3 b NH ( ) 2 CHO ( ) -1 d HS ( ) -1 3 eN O ( ) ( ) ( ) 3 -1 4 -1 3 f HCO g HSO h HNO (a) As acid, OH -1 -2 +1 O + H + H H O NH + H NH H + OH H As base, OH -1 2 +1 (b) As acid, NH -1 +1 As base, NH + H +1 +1 34 (c) As acid, HO +1 - 2 As base, HO + +1 +1
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Nielsen Bhaskar/PC/1713K/A 2/05 3 3 (d) As acid, -1 +1 -2 HS H + S As base, 2 -1 +1 HS H H S +→ (e) Only as base, -1 +1 33 NO + H HNO (f) As acid, -1 +1 3 -2 3 HCO H + CO As base, -1 + 32 HCO + H H CO (g) As acid, 2 +1 44 HSO H SO →+ As base, +1 42 -1 HSO + H H SO 3 3 (h) As acid, +1 -1 HNO H + NO As base (rare), +1 +1 HNO + H H NO 6. Illustrate with equations two forms of representing the ionization of hydrazoic acid in water () 23 3 +1 -1 3aq aq HN + H O H O + N U 3 +1 -1 HN H + N U } Solution called hydrazoic acid 7. Write simplified equations to show all the theoretically possible steps in the ionization in water solution of each of the following. Also give the a b K or K expression for each ionization.
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This note was uploaded on 12/12/2011 for the course CHM 2041 taught by Professor Staff during the Fall '09 term at Santa Fe College.

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Ans_Ex7 - Nielsen CHM1041 Answer to Exercise set # 7 Ionic...

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