Worksheet Ch 13 answers 2021 PDF

Preview

Summary

Worksheet Ch 13 answers 2021-2022. Worksheet Ch 13 answers 2021-2022....

Description

CHAPTER_13 : WORKSHEET_Answers (Part 1) Solubility, energetics of solution formation, concentration units, Henry’s law Answer the following questions: 1. a. Predict whether iodine (I2) is more soluble in liquid ammonia (NH3) or in carbon disulfide (CS2). Answer : CS2 b. Which of the following should you expect to be more soluble in benzene than in water C3H8, HCl, I2, CS2? Answer : C3H8, I2, CS2 c. Which of the following solutions exhibits hydrogen bonding between the solute and solvent? (Select all that apply.) i H2(g) in H2O(l) ii CH3OH(l) in H2O(l) iii CO2(g) in H2O(l) iv NH3(g) in H2O(l) v. NaCl(s) in H2O(l) Answer: ii and iv 2. Which molecule would you expect to be more soluble in ethanol CH3CH2OH), CCl4 or CH2Cl2? Explain your choice. Answer: CH2Cl2 because it is polar solute and would dissolve more readily in a polar solvent like ethanol, whereas CCl4 is nonpolar and would dissolve more readily in a nonpolar solvent. 3. Between water and hexane (C6H14), pick an appropriate solvent to dissolve each of the following solutes: a. methanol (CH3OH), b. lithium nitrate, c. coconut oil, d. acetic acid (CH3COOH), e. toluene (C7H8), and f. dimethyl ether (H3C–O–CH3). State the kind of intermolecular forces that would occur between the solute and solvent in each case. Answer: a) water (H-bonding); b) water (ion-dipole); c) hexane dispersion); d) water (H-bonding); e) hexane (dispersion); f) water (dipole-dipole)

4. The enthalpy of solution for cesium fluoride is –36.8 kJ/mol. What can you conclude about the relative magnitudes of ΔHsolute and ΔHhydration? Answer: |ΔHhydration | > |ΔHsolute |

5. Silver nitrate has a heat of hydration of –843 kJ/mol and a heat of solution of –23 kJ/mol. What is the lattice energy of silver nitrate? Answer: –820. kJ/mol 6. Potassium nitrate has a lattice energy of -163.8 kcal/mol and a heat of hydration of -155.5 kcal /mol. How much potassium nitrate has to dissolve in water, at room temperature, to absorb 1.00 x 102 kJ of heat? (1 cal = 4.184 J) Answer: 2.91 x 102 g 7. How many milliliters of water (d = 0.998 g/mL) are required to dissolve 25.0 g of urea and thereby produce a 1.65 m solution of urea (CO(NH2)2)? Answer: 251 mL 8. Calculate a) the molality of CH3OH (methanol) and b) mole fraction of solvent in a solution that is 7.50% by mass CH3OH in CH3CH2OH (ethanol). Answer: a) 2.53 m; b) 0.896 9. At 25.0 °C, an aqueous solution that is 25.0% H2SO4 by mass has a density of 1.178 g/mL. Calculate the a) molarity and b) molality of this solution Answer: a) 3.00 M; b) 3.40 m 10. A 2.90 m solution of methanol (CH3OH) in water has a density of 0.984 g/mL What are the a) mass percent, b) molarity, and c) mole percent of solute in this solution? Answer: a) 8.50 methanol by mass; b) 2.61 M; c) 4.96 mol % methanol 11. Calculate the pressure of O2 necessary to generate an aqueous solution that is 3.4×10-2 M in O2 at 25 °C given that the Henry’s law constant for O2 in water at 25 °C is 1.3×10-3 mol/L∙atm. Answer: 26 atm 12. What mass of O2 is dissolved in 1.00 L of water at 25 °C under atmospheric conditions where the partial pressure of O2 is 0.22 atm. The Henry’s law constant for O2 in water at 25 °C is 1.3×10-3 mol/L∙atm. Answer: 9.2 mg 13. At 25 °C and 1 atm of CO2 pressure, the solubility of CO2 (g) is 149 mg CO2/100 g water. When air at 25 °C and 1 atm is in equilibrium with water, what is the molar concentration of dissolved CO2 given that air contains 0.037 mole percent CO2(g)? The density of water at 25 °C is 0.997 g/mL. Answer : 1.2 x 10-5 M 14. The solubility of N2 in blood at 37°C and at a partial pressure of 0.80 atm is 5.6 × 10−4 mol/L. A deep-sea diver breathes compressed air with the partial pressure of N2 equal to 4.0 atm. Assume that the total volume of blood in the body is 5.0 L. Calculate the amount of N2 gas released at 37°C when the diver returns to the surface of the water, where the partial pressure of N2 is 0.80 atm. Answer : 1.1  102 mol

CHAPTER_13 : WORKSHEET (Part 2) colligative properties of solutions (Raoult’s law, FP, BP, and OP) Answer the following questions: 1. At 25 °C, the vapor pressure of pure benzene (C6H6) and pure toluene (C7H8) are 95.1 and 28.4 mmHg, respectively. A solution is prepared that has equal masses of C 6H6 and C7H8. Determine the total vapor pressure above this solution. Answer: 64.2 mmHg 2. a. Calculate the mass of glucose (C6H12O6) that should be dissolved in 655 g of water at 37 °C to cause a change in the vapor pressure by 5.2 mmHg given that the vapor pressure of pure water at 37 °C is 42.2 mmHg. b. What mass of NaCl should be dissolved in water to cause the change in vapor pressure described in part a)? Answer: a. 9.2×102 g glucose; b. 1.5×102 g NaCl 3. What is the boiling point of an aqueous solution of sucrose, C12H22O11 (aq), that has a freezing point of -1.36 °C. For water, Kb = 0.512 °C/m and Kf = 1.86 °C/m. Answer: 100.374 °C 4. A solution of hydrofluoric acid was prepared by dissolving 0.500 mol HF in 2.00×102 g water. What is the boiling point of this solution if only 50.0% of the acid dissociates? The Kb for water is 0.512 °C/m. Answer: 101.92 °C 5. What is the freezing point of an aqueous aluminum nitrate solution that is 10.0 % aluminum nitrate by mass? Assume complete dissociation. Answer: -3.88 °C 6. 10.0 g of a non-electrolyte was dissolved in 115.0 g of benzene (C6H6) resulting in a solution that freezes at 0.70 °C. If the normal freezing point of benzene is 5.53 °C and its Kf = 5.12 °C/m, calculate the molar mass of the solute. Answer: 92.2 g/mol 7. Assuming complete dissociation, what mass of iron(III) chloride (molar mass = 162.20 g/mol) needs to be added 255 mL of water at 35 °C to cause an osmotic pressure of 2.60 mmHg? Answer: 1.40 mg 8. A quantity of 7.480 g of an organic compound is dissolved in water to make 300.0 mL of solution. The solution has an osmotic pressure of 1.43 atm at 27°C. The analysis of this compound shows that it contains 41.8 percent C, 4.7 percent H, 37.3 percent O, and 16.3 percent N. Calculate the molecular formula of the compound. Answer : C15H20O10N5. 9. A 0.036 M aqueous nitrous acid (HNO2) solution has an osmotic pressure of 0.93 atm at 25°C. Calculate the percent ionization of the acid. Answer : 5.6 %...