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General Chemistry Principles, Patterns, and Applications, 2011

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cell. The Na + , K + , Mg 2+ , <strong>and</strong> Ca 2+ ions are all transported using this mechanism. Which of these ions would be<br />

captured by<br />

a. oxygen donors with a neutral or low (−1) charge?<br />

b. carboxylates, phosphates, <strong>and</strong> some neutral oxygen donors?<br />

c. polyphosphates with a total negative charge greater than −2?<br />

d. nitrogen donors?<br />

17. Sodium carbonate has long been used in the glass industry, for making water softeners, <strong>and</strong> in the wood pulp<br />

<strong>and</strong> paper industries. Recently, sodium carbonate has proved useful for removing SO 2 <strong>and</strong> H 2 SO 4 from the<br />

flue gases of coal- <strong>and</strong> oil-fired power stations. Write balanced chemical equations showing the reactions<br />

that occur when flue gases are passed through solid sodium carbonate.<br />

18. Hard water contains high concentrations of Ca 2+ <strong>and</strong> Mg 2+ . These ions react with soaps (sodium <strong>and</strong><br />

potassium salts of naturally occurring carboxylic acids) to form an insoluble scum. Explain how adding<br />

Na 2 CO 3 to hard water can soften the water <strong>and</strong> improve the ability of soaps to remove dirt <strong>and</strong> grime.<br />

19. Do you expect MgCO 3 or Mg(OH) 2 to be more soluble in water? Based on your answer, explain how adding<br />

Ca(OH) 2 softens water by removing Mg 2+ . Be sure to show a balanced chemical equation for the reaction.<br />

20. How does a low-sodium diet help lower blood pressure? Do you think a diet high in KCl would also be<br />

effective at lowering blood pressure? Explain your answer.<br />

A N S W E R S<br />

1.<br />

a. BeCO 3 ; less stable to decomposition due to small size of Be 2+<br />

b. Be; low Z results in little absorption of x-rays<br />

c. BaI 2 ; has greater ionic character<br />

d. Mg; smaller size results in stronger polar covalent bonds to carbon<br />

e. MgO; higher lattice energy <strong>and</strong> melting point<br />

2.<br />

3.<br />

4.<br />

5. KO 2 ; the reaction is 4KO 2 (s) + 4CO 2 (g) + 2H 2 O(g) → 4KHCO 3 (s) + 3O 2 (g).<br />

6.<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

1980

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