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Problem 109
A solution is made 1.1⨉10-3 M in Zn(NO3)2 and 0.150 M in NH3. After the solution reaches equilibrium, what concentration of Zn2+(aq) remains?
Problem 111
Use the appropriate values of Ksp and Kf to find the equilibrium constant for the reaction. FeS(s) + 6 CN-(aq) ⇌ Fe(CN)64-(aq) + S2-(aq)
Problem 112
Use the appropriate values of Ksp and Kf to find the equilibrium constant for the reaction. PbCl2(s) + 3 OH-(aq) ⇌ Pb(OH)3-(aq) + 2 Cl-(aq)
- Is the question formulated correctly?
Problem 113
- Calculate the pH of a solution made by combining 10.0 mL of 17.5 M acetic acid with 5.54 g of sodium acetate and diluting to a total volume of 1.50 L.
Problem 114
- A buffer is created by combining 150.0 mL of 0.25 M HCHO2 with 75.0 mL of 0.20 M NaOH. Determine the pH of the buffer.
Problem 115
- A buffer is created by combining 3.55 g of NH3 with 4.78 g of HCl and diluting to a total volume of 750.0 mL. Determine the pH of the buffer.
Problem 116
Problem 117
A 1.0-L buffer solution initially contains 0.25 mol of NH3 and 0.25 mol of NH4Cl. In order to adjust the buffer pH to 8.75, should you add NaOH or HCl to the buffer mixture? What mass of the correct reagent should you add?
- To adjust the pH of a 250.0-mL buffer solution initially containing 0.025 mol of HCHO2 and 0.025 mol of NaCHO2 to 4.10, should you add NaOH or HCl, and what mass of the correct reagent should you add?
Problem 118
Problem 119
In analytical chemistry, bases used for titrations must often be standardized; that is, their concentration must be precisely determined. Standardization of sodium hydroxide solutions can be accomplished by titrating potassium hydrogen phthalate (KHC8H4O4), also known as KHP, with the NaOH solution to be standardized. b. The titration of 0.5527 g of KHP required 25.87 mL of an NaOH solution to reach the equivalence point. What is the concentration of the NaOH solution?
- A 0.25-mol sample of a weak acid with an unknown pKa was combined with 10.0 mL of 3.00 M KOH, and the resulting solution was diluted to 1.500 L. The measured pH of the solution was 3.85. What is the pKa of the weak acid?
Problem 121
Problem 122
A 5.55-g sample of a weak acid with Ka = 1.3⨉10-4 was combined with 5.00 mL of 6.00 M NaOH, and the resulting solution was diluted to 750.0 mL. The measured pH of the solution was 4.25. What is the molar mass of the weak acid?
- From the data given—where a 0.552-g sample of ascorbic acid (vitamin C) is dissolved in water to a total volume of 20.0 mL and titrated with 0.1103 M KOH, the equivalence point occurred at 28.42 mL, and the pH of the solution at 10.0 mL of added base was 3.72—determine the molar mass and dissociation constant (Ka) for vitamin C.
Problem 123
- Calculate the pH at the beginning of the titration, at the equivalence point, at one-half of the equivalence point, and at 5.0 mL beyond the equivalence point to sketch the titration curve from Problem 123. Then, choose a suitable indicator for this titration from Table 17.1.
Problem 124
- If a hard water solution is saturated with calcium carbonate, what volume of the solution has to evaporate to deposit 1.00 × 10^2 mg of CaCO3, given that one of the main components of hard water is CaCO3, and when hard water evaporates, some of the CaCO3 is left behind as a white mineral deposit?
Problem 125
- If the sodium concentration in blood plasma is 0.140 M, and Ksp for sodium urate is 5.76 * 10^-8, what minimum concentration of urate would result in precipitation?
Problem 126
Problem 127
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?
Problem 128
Calculate the solubility of silver chloride in a solution that is 0.100 M in NH3.
Problem 129
Calculate the solubility of CuX in a solution that is 0.150 M in NaCN. Ksp for CuX is 1.27⨉10-36.
- The Kb of hydroxylamine, NH2OH, is 1.10 * 10^-8. A buffer solution is prepared by mixing 100.0 mL of a 0.36 M hydroxylamine solution with 50.0 mL of a 0.26 M HCl solution. Determine the pH of the resulting solution.
Problem 131
Problem 132
A 0.867-g sample of an unknown acid requires 32.2 mL of a 0.182 M barium hydroxide solution for neutralization. Assuming the acid is diprotic, calculate the molar mass of the acid.
Problem 133
A 25.0-mL volume of a sodium hydroxide solution requires 19.6 mL of a 0.189 M hydrochloric acid for neutralization. A 10.0-mL volume of a phosphoric acid solution requires 34.9 mL of the sodium hydroxide solution for complete neutralization. Calculate the concentration of the phosphoric acid solution.
- What is the mass of sodium formate required to be dissolved in 250.0 cm³ of a 1.4 M formic acid solution to prepare a buffer solution with a pH of 3.36?
Problem 134
- What relative masses of dimethylamine and dimethylammonium chloride are needed to prepare a buffer solution with a pH of 10.43?
Problem 135
- You are asked to prepare 2.0 L of an HCN/NaCN buffer that has a pH of 9.8 and an osmotic pressure of 1.35 atm at 298 K. What masses of HCN and NaCN should you use to prepare the buffer? (Assume complete dissociation of NaCN.)
Problem 136
Problem 137
What should the molar concentrations of benzoic acid and sodium benzoate be in a solution that is buffered at a pH of 4.55 and has a freezing point of -2.0 °C? (Assume complete dissociation of sodium benzoate and a density of 1.01 g/mL for the solution.)