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- Using the qualitative analysis flowchart in Figure 17.18
Problem 136
, tell how you could separate the following pairs of ions. (a) Ag+ and Cu2+
- Give a method for seperating the following pairs of ions by the addition of no more than two substances. (a) Hg2+ and Co2+
Problem 137
- Assume that you have three white solids: NaCl, KCl, and MgCl2. What tests could you do to tell which is which?
Problem 138
- In quantitative analysis, Ag+, Hg2+, and Pb2+ are seperated from other cations by the addition of HCl. Calculate the concentration of Cl-ions required to just begin the precipitation of (a) AgCl, (b) Hg2Cl2, (c) PbCl2 in a solution hav-ing metal-ion concentrations of 0.030 M. What fraction of the Pb2+ remains in solution when the Ag+ just begins to precipitate?
Problem 139
- 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?
Problem 140
- Calculate the molar solubility of MnS in a 0.30 M NH4Cl - 0.50 M NH3 buffer solution that is saturated with H2S ([H2S] ≈ 0.10 M). What is the solubility of MnS (in g/L)? (Ksp for MnS is 3 x 10^-7.)
Problem 141
- A 100.0 mL sample of a solution that is 0.100 M in HCl and 0.100 M in HCN is titrated with 0.100 M NaOH. Calculate the pH after the addition of the following volumes of NaOH: (b) 75.0 mL
Problem 143
- 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?
Problem 144
- A type of kidney stone is a precipitate of calcium oxalate (CaC2O4, Ksp = 2.3 x 10^-9). A urine sample has a Ca2+ concentration of 2.3 x 10^-3 M and an oxalic acid (H2C2O4, Ka1 = 5.9 x 10^-2, Ka2 = 6.4 x 10^-5) concentration of 1.1 x 10^-4 M. (a) A typical pH for urine is 5.5. Will a precipitate of calcium oxalate form under these conditions? (b) A vegetarian diet results in a higher pH for urine, typically greater than 7. Would kidney stones be more or less likely to form in urine with higher pH?
Problem 145
- When a typical diprotic acid H2A (Ka1 = 10^-4, Ka2 = 10^-10) is titrated with NaOH, the principal A-containing species at the first equivalence point is HA-. (b) Assuming that this is the principal reaction, show that the pH at the first equivalence point equals the average of pKa1 and pKa2. (c) How many A2- ions are present in 50.0 mL of 1.0 M NaHA?
Problem 146
- Ethylenediamine (NH2CH2CH2NH2, abbreviated en) is an organic base that can accept two protons: (a) Consider the titration of 30.0 mL of 0.100 M ethylenediamine with 0.100 M HCl. Calculate the pH after the addition of the following volumes of acid, and construct a qualitative plot of pH versus milliliters of HCl added: (i) 0.0 mL (ii) 15.0 mL (iii) 30.0 mL (iv) 45.0 mL (v) 60.0 mL (vi) 75.0 mL
Problem 147
- What is the pH of the mixture before the addition of any base?
Problem 148
Problem 148a
A 40.0 mL sample of a mixture of HCl and H3PO4 was titrated with 0.100 M NaOH. The first equivalence point was reached after 88.0 mL of base, and the second equivalence point was reached after 126.4 mL of base. (a) What is the concentration of H3O+ at the first equivalence point?
Problem 148b
A 40.0 mL sample of a mixture of HCl and H3PO4 was titrated with 0.100 M NaOH. The first equivalence point was reached after 88.0 mL of base, and the second equivalence point was reached after 126.4 mL of base. (b) What are the initial concentrations of HCl and H3PO4 in the mixture?
Problem 148c
A 40.0 mL sample of a mixture of HCl and H3PO4 was titrated with 0.100 M NaOH. The first equivalence point was reached after 88.0 mL of base, and the second equivalence point was reached after 126.4 mL of base. (c) What percent of the HCl is neutralized at the first equivalence point?
Problem 148f
A 40.0 mL sample of a mixture of HCl and H3PO4 was titrated with 0.100 M NaOH. The first equivalence point was reached after 88.0 mL of base, and the second equivalence point was reached after 126.4 mL of base. (f) What indicators would you select to signal the equivalence points?
- A 1.000 L sample of HCl gas at 25°C and 732.0 mm Hg was absorbed completely in an aqueous solution that contained 6.954 g of Na2CO3 and 250.0 g of water. (a) What is the pH of the solution?
Problem 149
- 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?
Problem 150
- Consider the reaction that occurs on mixing 50.0 mL of 0.560 M NaHCO3 and 50.0 mL of 0.400 M NaOH at 25 °C. (a) Write a balanced net ionic equation for the reaction. (b) What is the pH of the resulting solution?
Problem 151
Problem 152a
In qualitative analysis, Ca2+ and Ba2+ are seperated from Na+, K+, Mg2+ by adding aqueous (NH4)2CO3 to a solution that also contains aqueous NH3 (Figure 17.18). Assume that the concentrations after mixing are 0.080 M (NH4)2CO3 and 0.16 M NH3. (a) List all the Bronsted-Lowry acids and bases present initially, and identify the principal reaction.
- A railroad tank car derails and spills 36 tons of concentrated sulfuric acid. The acid is 98.0 mass% H2SO4 and has a density of 1.836 g/mL. (c) How many liters of carbon dioxide at 18 °C and 745 mm Hg are produced as a by-product?
Problem 153
Problem 153a
A railroad tank car derails and spills 36 tons of concentrated sulfuric acid. The acid is 98.0 mass% H2SO4 and has a density of 1.836 g/mL. (a) What is the molarity of the acid?
Problem 153b
A railroad tank car derails and spills 36 tons of concentrated sulfuric acid. The acid is 98.0 mass% H2SO4 and has a density of 1.836 g/mL. (b) How many kilograms of sodium carbonate are needed to completely neutralize the acid?
- 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?
Problem 154
Problem 154a
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 hair, 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. (a) Assuming that 30% of the Pb(CH3CO2)2 is converted to PbS, how many milligrams of PbS are formed per application of the coloring solution?
- Neutralization reactions involving either a strong acid or a strong base go essentially to completion, and therefore we must take such neutralizations into account before calculating concentrations in mixtures of acids and bases. Consider a mixture of 3.28 g of Na3PO4 and 300.0 mL of 0.180 M HCl. Write balanced net ionic equations for the neutralization reactions and calculate the pH of the solution.
Problem 156
- Consider a galvanic cell that utilizes the following half-reactions:
Problem 159
(d) Will AgCl precipitate if 10.0 mL of 0.200 M NaCl is added to the solution in part (c)? Will AgBr precipitate if 10.0 mL of 0.200 M KBr is added to the resulting solution?