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17 Additional Aspects of Solutions to Exercises Aqueous Equilibria 17.95 (a) H₂CO₃(aq) A person breathing normally exhales CO₂(g). Rapid breathing causes excess (g) to be removed from the blood. By LeChatelier's principle, this causes both equilibria above to shift right, reducing in the blood and raising blood pH. (b) Breathing in a paper bag traps the exhaled CO₂; the gas in the bag contains more than ambient air. When a person inhales gas from the bag, a greater amount (partial pressure) of CO₂(g) in the lungs shifts the equilibria left, increasing and lowering blood pH. 17.96 (a) CdS: 8.0 CuS: 6 CdS has greater molar solubility. (b) 7.4 BaCrO₄: 2.1 10⁻¹⁰ BaCrO₄ has greater molar solubility. (c) Since the stoichiometry of the two complexes is not the same, values can't be compared directly; molar solubilities must be calculated from Kₛₚ values. Ni(OH)₂: = 6.0 10⁻¹⁶ = [Ni²⁺] = x, = 2x Note that [OH⁻] from the autoionization of water is less than 1% of [OH⁻] from Ni(OH)₂ and can be neglected. = 1.3 = [Ni²⁺] = [CO₃²⁻] = NiCO₃ has greater molar solubility than Ni(OH)₂, but the values are much closer than expected from inspection of values alone. (d) Again, molar solubilities must be calculated for comparison. has greater molar solubility than 17.97 (a) s² = 4.5 S = 6.708 10⁻⁵ = 6.7 10⁻⁵ (b) CaCO₃(s) 1L Kb 1L K Kb = for 541