AP Chemistry Name :
Worksheet : Ch 11-1 Date :
A. Multiple choice : Calculators may not be used on the multiple choice questions.
_____ 1. What volume of 0.10 M Ba(OH)2 is needed to neutralize 25.0 mL of a 0.20 M nitric acid solution?
a. 50.0 mL b. 40.0 mL c. 30.0 mL d. 25.0 mL e. 10.0 mL
_____ 2. Carbon dioxide reacts with water to form carbonic acid. Carbonic acid, in turn, reacts with sodium hydroxide. What maximum mass of carbon dioxide can be removed from a stream of waste gases by 2000. liters of a 0.10 M solution of sodium hydroxide?
a. 1.1 kg b. 2.2 kg c. 3.3 kg d. 4.4 kg e. 8.8 kg
_____ 3. Silver chloride is least soluble in a 0.10 M solution of which of the following?
a. Al(NO3)3 b. NaCl c. Al2(CO3)3 d. MgSO4 e. MgI2
_____ 4. In a titration of acetic acid by a standardized solution of 0.12 M NaOH, a drop of the 0.12 M NaOH is left hanging from the tip of the buret at the end point. This will cause the calculation of the molarity of the acetic acid to be
a. too high b. too low c. will not matter d. not enough information given
_____ 5. In a titration of acetic acid by a standardized solution of 0.12 M NaOH, a 25.0 mL sample of the acetic acid was added to a 125 mL flask. A student measured 50 mL of distilled water using a beaker and added it to the acetic acid sample before adding the indicator. This will cause the calculation of the molarity of the acetic acid to be
a. too high b. too low c. will not matter d. not enough information given
_____ 6. Which of the following will increase in solubility in an acidic solution?
I. calcium carbonate III. magnesium phosphate V. calcium acetate
II. barium sulfate IV. magnesium nitrate
a. I and III b. I and IV c. IV and V d. I, II and III e II and V
_____ 7. To determine the molar mass of a monoprotic acid, a weighed sample was added to a flask, dissolved in a sample of distilled water and titrated with 0.10 M KOH. If some of the weighed sample remained on the weighing paper (and not added to the flask), the molar mass would be
a. too high b. too low c. will not matter d. not enough information given
_____ 8. To determine the molar mass of a monoprotic acid, a weighed sample was added to a flask, dissolved in a sample of distilled water and titrated with 0.10 M KOH. If a volume of base is added beyond the equivalence point, the molar mass would be
a. too high b. too low c. will not matter d. not enough information given
_____ 9. If an aqueous solution of sodium chloride is changed from 20 ºC to 80 ºC, which of the following would be true?
I. The density would change.
II. The molarity would remain unchanged. IV. The mole fraction of the solute changes.
III The molality would remain unchanged. V. The vapor pressure would increase
a. II and IV b. I, II and III c. I, III and V d. I, II and V e. IV and V
_____ 10. A one liter solution is 0.10 M NaCl and 0.10 M MgCl2. What is the minimum mass of AgNO3 (molar mass = 169.9 g) must be added to precipitate out all of the chloride ions?
a. 5.1 g b. 51 g c. 3.4 g d. 34 g e. none of the above
11. Is molarity or molality dependent on temperature? Explain your answer. Why is molality, and not molarity, used in the equations describing freezing-point depression and boiling-point elevation?
12. A solution is prepared by dissolving 50.0 g cesium chloride (CsCl) in 50.0 g water. The volume of the solution is 63.3 mL. Calculate the mass percent, molarity, molality, and mole fraction of the cesium chloride.
13. A solution is prepared by mixing 50.0 mL toluene (C6H5CH3, d = 0.867 g/cm3) with 125 mL benzene (C6H6, d = 0.874 g/cm3). Assuming that the volumes add upon mixing, calculate the mass percent, mole fraction, molality, and molarity of the toluene.
14. A 1.37 M solution of citric acid (H3C6H5O7) in water has a density of 1.10 g/cm3. Calculate the mass percent, molality, mole fraction, and normality of the citric acid. Citric acid has three acidic protons.
15. The lattice energy (the energy change for : M+(g) + X-(g) à MX(s) )of KC1 is -715 kJ/mol, and the enthalpy of hydration is -684 kJ/mol. Calculate the enthalpy of solution per mole of solid KC1. Describe the process to which this enthalpy change applies.
16. a. Use the following data to calculate the enthalpy of hydration for cesium iodide and cesium hydroxide.
Lattice energy / ΔHsolnCsI(s) / -604 kJ/mol / 33 kJ/mol
CsOH(s) / -724 kJ/mol / -72 kJ/mol
b. Based on your answers to part A, which ion, OH- or I- is more strongly attracted to water?
17. Although A1(OH)3 is insoluble in water, NaOH is very soluble. Explain in terms of lattice energies.
18. The high melting points of ionic solids indicate that a lot of energy must be supplied to separate the ions from one another. How is it possible that the ions can separate from one another when soluble ionic compounds are dissolved in water, often with essentially no temperature change?
19. Choose which solvent, water or carbon tetrachloride, that you would use to dissolve each of the following :
a. Cu(NO3)2
b. CS2
c. CH3C-OH
║
O
d. CH3(CH2)16CH2OH
e. HCl
f. C6H6
20. What factors cause one solute to be more strongly attracted to water than another? For each of the following pairs, predict which substance would be more soluble in water.
a. CH3CH2OH or CH3CH2CH3
b. CHC13 or CC14
c. CH3CH2OH or CH3(CH2)14CH2OH
21. Rationalize the trend in water solubility for the following simple alcohols:
Answers : 12. 50.0% by mass, 4.69 M, 5.94 m, XCsI = 0.0967 13. 28.4 % toluene, Xtol = 0.252, m = 4.32, M = 2.69 14. 23.9%, 1.64 m, XCitric acid = 0.0287, 4.11 N 16a. ΔHhyd for CsI = -571 kJ , ΔHhyd for CsOH = -796 kJ 16b. The enthalpy of hydration for CsOH is ore exothermic, indicating a stronger (more stable, lower energy) bond 17. Both are ionic, although the larger charge of the Al3+ ion gives it a greater lattice energy that cannot be overcome by the attraction of the water molecules. In NaOH the lattice energy is smaller than the favorable enthalpy of hydration, so it dissolves. 19. water : a, c and e CCl4 – b, d and f 20. Polarity, which creates hydrogen bonding and dipole. a. CH3CH2OH b. CHCl3 c. CH3CH2OH 21. As the length of the molecule increases, the polarity decreases reducing hydrogen bonding.
15. KCl(s) ( K+(g) + Cl-(g) ΔH = 715 kJ/mol
K+(g) + Cl-(g) à K+(aq) + Cl-(aq) ΔH = -684 kJ/mol
KCl(s) à K+(aq) + Cl-(aq) ΔH = 31 kJ/mol