18. Aqueous Equilibrium

Determine the molar solubility of CaCO₃ in a solution of 0.500 M Na₂CO₃. K_sp for CaCO₃ is 4.96 × 10⁻⁹.

What is the molar solubility of PbBr₂ in pure water? K_sp for PbBr₂ is 4.67 × 10⁻⁶.

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]

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]

What is the solubility-constant expression for Ca3(PO4)2 (s)? (a) [Ca2+]3 [PO43-]2 (b) [Ca2+]3 [PO43-]2 / [Ca3(PO4)2] (c) [Ca(PO4)2] / [Ca2+]3 [PO43-]2 (d) [Ca2+]2 [PO43-]3

Which of these statements about the common-ion effect is most correct? (a) The solubility of a salt MA is decreased in a solution that already contains either M+ or A-. (b) Common ions alter the equilibrium constant for the reaction of an ionic solid with water. (c) The common-ion effect does not apply to unusual ions like SO32 - . (d) The solubility of a salt MA is affected equally by the addition of either A- or a noncommon ion.

Consider the equilibrium B1aq2 + H2O1l2 Δ HB+1aq2 + OH-1aq2. Suppose that a salt of HB+1aq2 is added to a solution of B1aq2 at equilibrium. (c) Will the pH of the solution increase, decrease, or stay the same?

What is the molar solubility of BaF2 in a solution containing 0.0750 M LiF (Ksp = 1.7 x 10^-6) (a) 2.3 x 10^-5 M (b) 3.0 x 10^-4 M (c) 1.2 x 10^-2 M (d) 1.3 x 10^-3 M

The following pictures represent solutions of Ag2CrO4, which also may contain ions other than Ag+ and CrO42- that are not shown. Solution 1 is in equilibrium with solid Ag2CrO4. Will a precipitate of solid Ag2CrO4 form in solutions 2-4? Explain.

(1)

(2)

(3)

(4)

The solubility of two slightly soluble salts of M2 + , MA and MZ2, is the same, 4 * 10-4 mol/L. (c) If you added an equal volume of a solution saturated in MA to one saturated in MZ2, what would be the equilibrium concentration of the cation, M2+?

(b) Write the expression for the solubility-product constant for each of the following ionic compounds: Cu31PO422.

(a) True or false: 'solubility' and 'solubility-product constant' are the same number for a given compound.

(a) I f t he molar solubility of CaF2 at 35 C i s 1.24 * 10-3 mol>L, what is Ksp at this temperature?

(b) If 0.0490 g of AgIO3 dissolves per liter of solution, calculate the solubility-product constant.

Does the pH increase, decrease, or remain the same when the substances are added to the solutions? (a) LiF to an HF solution (b) KI to an HI solution (c) NH4Cl to an NH3 solution

A 1.00-L solution saturated at 25 C with calcium oxalate 1CaC2O42 contains 0.0061 g of CaC2O4. Calculate the solubility-product constant for this salt at 25 C.

A 1.00-L solution saturated at 25 C with lead(II) iodide contains 0.54 g of PbI2. Calculate the solubility-product constant for this salt at 25 C.

Calculate the solubility of LaF3 in grams per liter in (a) pure water.

Consider a beaker containing a saturated solution of CaF2 in equilibrium with undissolved CaF21s2. Solid CaCl2 is then added to the solution. (a) Will the amount of solid CaF2 at the bottom of the beaker increase, decrease, or remain the same?

Calculate the solubility of Mn1OH22 in grams per liter when buffered at pH (b) 9.5.

Calculate the molar solubility of Ni1OH22 when buffered at pH (c) 12.0.

Calculate the molar solubility of Ni1OH22 when buffered at pH (b) 10.0.

Calculate the molar solubility of Ni1OH22 when buffered at pH (a) 8.0.

Calculate the minimum pH needed to precipitate Mn1OH22 so completely that the concentration of Mn2 +1aq2 is less than 1 mg per liter [1 part per billion (ppb)].

A solution of Na2SO4 is added dropwise to a solution that is 0.010 M in Ba2 +1aq2 and 0.010 M in Sr2 +1aq2. (b) Which cation precipitates first?

The water supply for a midwestern city contains the following impurities: coarse sand, finely divided particulates, nitrate ions, trihalomethanes, dissolved phosphorus in the form of phosphates, potentially harmful bacterial strains, dissolved organic substances. Which of the following processes or agents, if any, is effective in removing each of these impurities: coarse sand filtration, activated carbon filtration, aeration, ozonization, precipitation with aluminum hydroxide?

Write balanced equations and expressions for Ksp for the dissolution of each ionic compound. c. Ag2CrO4

Write balanced equations and expressions for Ksp for the dissolution of each ionic compound. b. PbBr2

Write balanced equations and expressions for Ksp for the dissolution of each ionic compound. a. BaSO4

Refer to the Ksp values in Table 17.2 to calculate the molar solubility of each compound in pure water. a. AgBr

Use the given molar solubilities in pure water to calculate Ksp for each compound. a. MX; molar solubility = 3.27 * 10 - 11 M

Use the given molar solubilities in pure water to calculate Ksp for each compound. b. PbF2; molar solubility = 5.63 * 10- 3 M

Use the given molar solubilities in pure water to calculate Ksp for each compound. b. Ag2SO3; molar solubility = 1.55 * 10- 5 M

Use the given molar solubilities in pure water to calculate Ksp for each compound. a. BaCrO4; molar solubility = 1.08 * 10- 5 M

The precipitation of Al(OH)3 (Ksp) = 1.3x10-33) is sometimes used ot purify water. (a) Estimate the pH at which precipitation of Al(OH)3 will begin if 5.0 lb of Al2(SO4)3 is added to 2000 gal of water

Two compounds with general formulas AX and AX2 have Ksp = 1.5 * 10 - 5. Which of the two compounds has the higher molar solubility?

Consider the compounds with the generic formulas listed and their corresponding molar solubilities in pure water. Which compound has the smallest value of Ksp? a. AX; molar solubility = 1.35 * 10 - 4 M b. AX2; molar solubility = 2.25 * 10- 4 M c. A2X; molar solubility = 1.75 * 10 - 4 M

The solubility of copper(I) chloride is 3.91 mg per 100.0 mL of solution. Calculate Ksp for CuCl.

Calculate the molar solubility of barium fluoride in each liquid or solution. a. pure water

Calculate the molar solubility of MX (Ksp = 1.27 * 10 - 36) in each liquid or solution. c. 0.20 M Na2 X

Calculate the molar solubility of calcium hydroxide in a solution buffered at each pH. c. pH = 9

Calculate the molar solubility of calcium hydroxide in a solution buffered at each pH. b. pH = 7

Lead(II) carbonate, PbCO3, is one of the components of the passivating layer that forms inside lead pipes. (d) The EPA threshold for acceptable levels of lead ions in water is 15 ppb. Does a saturated solution of lead(II) carbonate produce a solution that exceeds the EPA limit?

For each pair of compounds, use Ksp values to determine which has the greater molar solubility: (b) PbCO3 or BaCrO4.

Calculate the solubility (in grams per 1.00 * 102 mL of solution) of magnesium hydroxide in a solution buffered at pH = 10. How does this compare to the solubility of Mg(OH)2 in pure water?

For each of the following compounds, write a balanced net ionic equation for the dissolution of the compound in water, and write the equilibrium-constant expression for Ksp. (d) Hg2Cl2

The solubility of CaCO3 is pH dependent. (b) Use the Kb expression for the CO32 - ion to determine the equilibrium constant for the reaction CaCO31s2 + H2O1l2 ΔCa2 + 1aq2 + HCO3-1aq2 + OH-1aq2

Tooth enamel is composed of hydroxyapatite, whose simplest formula is Ca51PO423OH, 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, Ca51PO423F, whose Ksp = 1.0 * 10-60. (a) Write the expression for the solubility-constant for hydroxyapatite and for fluoroapatite.

A solution containing sodium fluoride is mixed with one containing calcium nitrate to form a solution that is 0.015 M in NaF and 0.010 M in Ca(NO3)2. Does a precipitate form in the mixed solution? If so, identify the precipitate.

Calculate the solubility of Mg1OH22 in 0.50 M NH4Cl.

A particular saturated solution of Ca3(PO4)2 has [Ca2+] = [PO43-] = 2.9 x 10^-7 M. (c) What is [PO43-] in a saturated solution that has [Ca2+] = 0.010 M?

The solubility-product constant for barium permanganate, Ba1MnO422, is 2.5 * 10-10. Assume that solid Ba1MnO422 is in equilibrium with a solution of KMnO4. What concentration of KMnO4 is required to establish a concentration of 2.0 * 10-8 M for the Ba2 + ion in solution?

Predict whether a precipitate will form if you mix 75.0 mL of a NaOH solution with pOH = 2.58 with 125.0 mL of a 0.018 M MgCl2 solution. Identify the precipitate, if any.

Use the following solubility data to calculate a value of Ksp for each compound. (d) Zn(CN)2; 4.95 x 10^-4 g/L

Use the following solubility data to calculate a value of Ksp for each compound. (a) SrF2: 1.03 x 10^-3 M

The solubility product constants of PbSO4 and SrSO4 are 6.3 * 10-7 and 3.2 * 10-7, respectively. What are the values of 3SO4 2 - 4, 3Pb2 + 4, and 3Sr2 + 4 in a solution at equilibrium with both substances?

Determine the minimum concentration of the precipitating agent on the right to cause precipitation of the cation from the solution on the left. c. 0.0018 M AgNO3; RbCl

Determine the minimum concentration of the precipitating agent on the right to cause precipitation of the cation from the solution on the left. b. 0.085 M CaI2; K2SO4

Determine the minimum concentration of the precipitating agent on the right to cause precipitation of the cation from the solution on the left. a. 0.035 M Ba(NO3)2; NaF

Use the values of Ksp in Appendix C to calculate the molar solubility of the following compounds: (b) Mg(OH)2

Use the values of Ksp in Appendix C to calculate the solubility of the following compounds (in g/L): (c) Cu3(PO4)2

Use Le Châtelier's principle to predict whether the solubility of BaF2 will increase, decrease, or remain the same on addition of each of the following substances. (d) Ba1NO322

Use Le Châtelier's principle to predict whether the solubility of BaF2 will increase, decrease, or remain the same on addition of each of the following substances. (c) NaNO3

Use Le Châtelier's principle to predict whether the solubility of BaF2 will increase, decrease, or remain the same on addition of each of the following substances. (b) KF

Use Le Châtelier's principle to predict whether the solubility of BaF2 will increase, decrease, or remain the same on addition of each of the following substances. (a) HCl

Calculate the molar solubility of PbCrO4 in: (a) Pure Water (d) 1.0 x 10^-3 M K2CrO4

The osmotic pressure of a saturated solution of strontium sulfate at 25 C is 21 torr. What is the solubility product of this salt at 25 C?

Is the solubility of Zn(OH)2 increased, decreased, or unchanged on addition of each of the following substances? Write a balanced net ionic equation for each dissolution reaction. (See Appendix C.6 for formulas of complex ions.) (a) HCl

A concentration of 10–100 parts per billion (by mass) of Ag+ is an effective disinfectant in swimming pools. However, if the concentration exceeds this range, the Ag+ can cause adverse health effects. One way to maintain an appropriate concentration of Ag+ is to add a slightly soluble salt to the pool. Using Ksp values from Appendix D, calculate the equilibrium concentration of Ag+ in parts per billion that would exist in equilibrium with (c) AgI.

Fluoridation of drinking water is employed in many places to aid in the prevention of tooth decay. Typically. the Fion concentration is adjusted to about 1 ppm. Some water supplies are also 'hard'; that is, they contain certain cations such as Ca2 + that interfere with the action of soap. Consider a case where the concentration of Ca2 + is 8 ppm. Could a precipitate of CaF2 form under these conditions? (Make any necessary approximations.)

Pseudogout, a condition with symptoms similar to those of gout (see Problem 126), is caused by the formation of calcium diphosphate (Ca2P2O7) crystals within tendons, cartilage, and ligaments. Calcium diphosphate will precipitate out of blood plasma when diphosphate levels become abnormally high. If the calcium concentration in blood plasma is 9.2 mg>dL, and Ksp for calcium diphosphate is 8.64 * 10 - 13, what minimum concentration of diphosphate results in precipitation?

Can Fe2+ be separated from Sn2+ by bubbling H2S through a 0.3 M HCl solution that contains 0.01 M Fe2+ and 0.01 M Sn2+? A saturated solution of H2S has [H2S] ≈ 0.10 M. Values of Kspa are 6 x 10^2 for FeS andd 1 x 10^-5 for SnS.

Will FeS precipitate in a solution that is 0.10 M in Fe(NO3)2, 0.4 M in HCl, and 0.10 M in H2S? Will FeS precipitate if the pH of the solution is adjusted to pH 8 with an NH4+ - NH3 buffer? Kspa = 6 x 10^2 for FeS.

(b) If Ksp = 1.1 * 10-12 for Ag2CrO4, what are the molar concentrations of Ag+ and CrO4 2-in solution?

Write the expression for the solubility product constant of MgF2 (see Problem 4.139). If [Mg2+] = 2.6 * 10-4 mol/L in a solution, what is the value of Ksp?

A 0.0100 mol sample of solid Cd(OH)2 (Ksp = 5.3 x 10^-15) in 100.0 mL of water is titrated with 0.100 M HNO3. (c) How many milliliters of 0.100 M HNO3 must be added to completely neutralize the Cd(OH)2?

A saturated solution of an ionic salt MX exhibits an osmotic pressure of 74.4 mm Hg at 25 °C. Assuming that MX is completely dissociated in solution, what is the value of its Ksp?

Some progressive hair coloring products marketed to men, such as Grecian Formula 16, contain lead acetate Pb(CH3CO2)2. As the coloring solution is rubbed on the hhair, the Pb2+ ions react with the sulfur atoms in hair proteins to give lead(II) sulfide (PbS), which is black. A typical coloring solution contains 0.3 mass% Pb(CH3CO2)2, and about 2 mL of the solution is used per application. (b) Suppose the hair is washed with shampoo and water that has pH = 5.50. How many washings would be required to remove 50% of the black color? Assume that 3 gal of water is used per washing and that the water becomes saturated with PbS. (c) Does the calculated number of washings look reason-able, given that frequent application of the coloring solution is recommended? What process(es) in addition to dissolution might contribute to the loss of color?