A. 6.40 x 10-2 M B. 0.100 M C. 0.128 M D. 0.256 M
2. A sample of 50.0 mL of 0.10 M NH3 (Kb = 1.8 x 10-5) is titrated with 0.10 M HCl. Calculate the pH at the equivalence point.
A. 6.98 B. 2.87 C. 7.78 D. 5.28
3. Consider the titration curve shown below. Which of the following best describes the titration?
4. Which of the following solutions will act as buffer solutions?
1. 10 mL of 0.1 M NaOH + 5 ml of 0.1 M HCl 2. 10 mL of 0.1 NaOH + 15 ml of 0.1 M CH3COOH 3. 10 ml of 0.1 NH3 + 10 ml of 0.1 M NH4Cl 4. 10 mL of 0.05 M NaF + 5 mL of 0.1 M HF
A. 1 and 2. B. 3 and 4. C. 2, 3 and 4. D. All will act as buffer solutions.
5. What is the molar concentration of H3O+ in 500. mL of a solution containing 1.0 mole of HNO3?
A. 0.25 B. 1.0 C. 0.50 D. 2.0
6. If an indicator is to be used in an acid base titration having an equivalence point in the pH range 8 to 10, the indicator must
A. be a weak base. B. have a Ka of about 1 x 10-9. C. ionize in two steps. D. be added to the solution only after the solution has become alkaline.
7. Which of the following will be more soluble when the pH of the solution is decreased?
A. 1 and 2 B. 2 and 3 C. 3 and 4 D. 1 and 4
8. What is [H+] in mol/L of a solution that is 0.20 M in CH3COONa and 0.10 M in CH3COOH? Ka for CH3COOH = 1.8 x 10-5.
A. 9.0 x 10-6 B. 3.5 x 10-4 C. 1.1 x 10-5 D. 1.8 x 10-5
9. H2SO3 is a diprotic acid with
What is Kb for the sulfite ion, SO32-?
A. 1.0 x 10-6 B. 1.0 x 10-7 C. 2.3 x 10-8 D. 1.5 x 10-2
10. A solution was prepared by mixing 10.0 mL of 0.50 M NaOH with 10.0 mL of 1.00 M acetic acid, Ka = 1.8 x 10-5. Find the pH of the solution.
A. 2.45 B. 1.67 C. 2.37 D. 4.74
11. What is the hydrogen-ion concentration in a 1.00 M solution of H2SO4? (Ka2 for H2SO4 is 1.2 x 10-2).
A. 0.50 M B. 1.01 M C. 1.51 M D. 1.99 M
12. Calculate the number of moles of NH4Cl that must be added to 1.0 L of 0.10 M NH3 (Kb = 1.8 x 10-5) to prepare a buffer of pH 9.00.
A. 0.056 mol B. 0.10 mol C. 0.18 mol D. 0.26 mol
13. Which of the following are amphoteric?
A. Al(OH)3(s) and Fe(OH)3(s). B. Al(OH)3(s) and HCO3-(aq). C. Ba(OH)2(s) and NaOH(aq). D. None of the above.
14. Which of the following are not state functions?
A. 1 and 4 B. 2 and 3 C. 2, 3 and 4 D. 1, 2 and 3
15. Consider the reaction
If 100. moles of H2O2 decomposes at 1 atm pressure and 298 K, how much work is done by the O2(g) as it expands against the atmosphere?
A. 2.44 x 101 L-atm C. 1.22 x 103 L-atm B. 2.44 x 103 L-atm D. 4.89 x 103 L-atm
16. Which of the following statements is false?
A. In a spontaneous process, delta Ssys is always > 0. B. The First Law of Thermodynamics states that the total energy in the universe is constant. C. Entropy is a measure of the disorder or randomness of a system. D. For a system at equilibrium, delta G = 0.
17. Which of the following is a chemical equation that defines a standard heat of formation?
A. N2(g) + 3 H2(g) = 2 NH3(g) B. S(s) + H2(g) + 2 O2(g) = H2SO2(l) C. SO2(g) + 1/2 O2(g) = SO3(g) D. C(diamond) + O2(g) = CO2(g)
18. Which of the following reactions exhibits an increase in entropy?
A. H2(g) + S(s) = H2S(g) B. 2 Al(s) + 3 O2(g) = Al2O3(s) C. 3 H2(g) + N2(g) = 2 NH3(g) D. 2 H2O(l) = 2 H2(g) + O2(g)
19. The best measure of the spontaneity of a process is
A. the change in the number of moles of gaseous species. B. the change in entropy of the process. C. the change in enthalpy of the process. D. the change in free energy of the process.
20. For a certain reaction, delta Go = +45 kJ/mol and delta Ho = +90 kJ/mol at 0oC. At what temperature (K) is delta Go = 0, assuming that delta Ho and delta So are independent of temperature?
A. 273 K B. 298 K C. 546 K D. 596 K
21. The calculated value of delta So is positive for the exothermic reaction:
Therefore, this reaction is:
A. non-spontaneous at all temperatures. B. spontaneous only at high temperatures. C. spontaneous only at low temperatures. D. spontaneous at all temperatures.
22. Given the data below, calculate the equilibrium constant at 25oC for the reaction: 2 NO2(g) = N2O4(g).
Compound delta G(kJ/mol) NO(g) 86.55 NO2(g) 51.29 N2O(g) 104.18 N2O4(g) 97.82
A. Keq = 6.8 B. Keq = 1.3 C. Keq = 1.0 D. Keq = 0.15
23. Consider the reaction
If delta Go = -5.39 kJ and Kp = 8.81 for the reaction at 20oC, calculate the value of delta G for the reaction when the partial pressures of NO2 and N2O4 are 1.50 atm and 2.40 atm, respectively.
A. -5.22 kJ B. +4.71 kJ C. -9.28 kJ D. +154 kJ
24. A chemical reaction is not spontaneous at any temperature when
A. both the enthalpy and the entropy change are negative. B. both the enthalpy and the entropy change are positive. C. the enthalpy change is positive and the entropy change is negative. D. the enthalpy change is negative and the entropy change is positive.
25. If delta Hvapo = 30.8 kJ/mol and delta Svapo = 87.2 J/mol K for benzene, C6H6, what is the boiling point of benzene? Assume delta Hvap0 and delta Svapo are independent of temperature.
A. 0.35oC B. 353.oC C. 80.oC D. 1.0oC