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- Tooth enamel is composed of hydroxyapatite, whose simplest formula is Ca5(PO4)3OH, and whose corresponding Ksp = 6.8 × 10^(-27). As discussed in the Chemistry and Life box on page 746, fluoride in fluorinated water or in toothpaste reacts with hydroxyapatite to form fluoroapatite, Ca5(PO4)3F, whose Ksp = 1.0 × 10^(-60). (b) Calculate the molar solubility of each of these compounds.
Problem 1
Problem 2a
The beaker on the right contains 0.1 M acetic acid solution with methyl orange as an indicator. The beaker on the left contains a mixture of 0.1 M acetic acid and 0.1 M sodium acetate with methyl orange. (a) Using Figures 16.8 and 16.9, which solution has a higher pH?
Problem 2b
The beaker on the right contains 0.1 M acetic acid solution with methyl orange as an indicator. The beaker on the left contains a mixture of 0.1 M acetic acid and 0.1 M sodium acetate with methyl orange. (b) Which solution is better able to maintain its pH when small amounts of NaOH are added? Explain. [Sections 17.1 and 17.2]
Problem 3
A buffer contains a weak acid, HA, and its conjugate base. The weak acid has a pKa of 4.5, and the buffer has a pH of 4.3. Without doing a calculation, state which of these possibilities are correct at pH 4.3. (a) 3HA4 = 3A-4, (b) 3HA4 7 3A-4, or (c) 3HA4 6 3A-4. [Section 17.2]
Problem 4a
The following diagram represents a buffer composed of equal concentrations of a weak acid, HA, and its conjugate base, A-. The heights of the columns are proportional to the concentrations of the components of the buffer. (a) Which of the three drawings, (1), (2), or (3), represents the buffer after the addition of a strong acid? [Section 17.2]
Problem 4c
The following diagram represents a buffer composed of equal concentrations of a weak acid, HA, and its conjugate base, A-. The heights of the columns are proportional to the concentrations of the components of the buffer. (c) Which of the three represents a situation that cannot arise from the addition of either an acid or a base? [Section 17.2]
Problem 5b
The following figure represents solutions at various stages of the titration of a weak acid, HA, with NaOH. (The Na+ ions and water molecules have been omitted for clarity.) To which of the following regions of the titration curve does each drawing correspond: (b) after addition of NaOH but before the equivalence point? [Section 17.3]
- Consider a beaker containing a saturated solution of PbI2 in equilibrium with undissolved PbI2(s). Now solid KI is added to this solution. (a) Will the amount of solid PbI2 at the bottom of the beaker increase, decrease, or remain the same? (b) Will the concentration of Pb2+ ions in solution increase or decrease? (c) Will the concentration of I- ions in solution increase or decrease?
Problem 6
Problem 6a
Match the following descriptions of titration curves with the diagrams: (a) strong acid added to strong base. [Section 17.3]
Problem 6d
Match the following descriptions of titration curves with the diagrams: (d) strong base added to polyprotic acid. [Section 17.3]
- (a) Will Co(OH)2 precipitate from solution if the pH of a 0.020 M solution of Co(NO3)2 is adjusted to 8.5? (b) Will AgIO3 precipitate when 20 mL of 0.010 M AgNO3 is mixed with 10 mL of 0.015 M NaIO3? The Ksp of AgIO3 is 3.1 * 10^-8.
Problem 7
Problem 9a
The following graphs represent the behavior of BaCO3 under different circumstances. In each case, the vertical axis indicates the solubility of the BaCO3 and the horizontal axis represents the concentration of some other reagent. (a) Which graph represents what happens to the solubility of BaCO3 as HNO3 is added? [Section 17.5]
Problem 10b
Ca1OH22 has a Ksp of 6.5 * 10-6. (b) If 50 mL of the solution from part (a) is added to each of the beakers shown here, in which beakers, if any, will a precipitate form? In those cases where a precipitate forms, what is its identity? [Section 17.6]
