Practice Exams ChE - 15

1. Given the equilibrium reaction at 250 ?C and 1 atm, PCl5 (g) <-> PCl3 (g) + Cl2 (g). The density was found to be 4.4 g/L. The fraction of PCl5 dissociates is
a. 0.81
b. 0.093
c. 0.103
d. 0.42
e. none of the above

2. The solubility product constant is valid:
a. for all soluble compounds
b. for all insoluble salts
c. only of saturated solutions
d. only for fairly insoluble electrolytes
e. only for fairly soluble electrolytes

3. 55,000 gallons of water passes through a heat exchanger and absorbs 28,000,000 Btu. The exit temperature is 110 degF. The entrance water temperature is nearest to
a. 49
b. 56
c. 68
d. 73
e. none of the above

4. If 5.0 grams of KMnO4 are dissolved in 1 L solution, the normality when used for titration in acid medium is
a. 0.0316
b. 0.2215
c. 0.1582
d. 0.0949
e. 0.4469

5. The maximum thermal efficiency that can be obtained in an ideal reversible heat engine operating between 300 degC and 100 degC is
a. 0.67
b. 0.35
c. 0.54
d. 0.82
e. none of the above

6. Which of the following statements is not correct?
a. The absolute temperature of a gas is directly proportional to its volume at constant P.
b. Nitrogen will diffuse faster than oxygen gas at fixed T & P.
c. The product of P & V of a fixed amount of gas is constant.
d. Most gases are cold during a free adiabatic expansion.
e. None of the above

7. A compound whose molecules are not associated by H-bonding is
a. CH3OH
b. CH3NH2
c. (CH3)3N
d. HCOOH
e. HCONH2

8. The most probable valence of an element with an electronic configuration of 1s2 2s2 2p6 3s2 3p5 is
a. +1
b. +2
c. +3
d. –2
e. –1

9. The process that has no heat transfer is called
a. isentropic
b. isothermal
c. quasistatic
d. polytropic
e. none of the above

10. A 1.0 gram sample of impure K2CO3 is taken for analysis. The solution of the dissolved sample required 58.10 mL of 0.14 N HCl. However, 0.65 mL of NaOH was needed for back titration (1 mL of HCl is equivalent to 2.60 mL NaOH). Calculate the purity of the sample expressed as % K2O.
a. 38.14%
b. 40.23%
c. 34.4%
d. 42.1%
e. 36.7%