Test 2 Reviewer CHEM 1411 CHAPTERS 4,5,6

1. A sample of methane, CH4, occupies a volume of 170.0mL at 25°C and exerts a pressure of 965.0mmHg. If the volume of the gas is allowed to expand to 720.0mL at 298 K, what will be the pressure of the gas?

A) / 4090 mmHg
B) / 2720 mmHg
C) / 227.8 mmHg
D) / 0.008823 mmHg
E) / 550.0 mmHg

2. Which of the following is a correct statement of Charles’s law, ?

A) / The volume of a gas varies proportionally with the pressure.
B) / The volume of a gas sample varies directly with the absolute temperature.
C) / All gas samples of the same volume at STP contain the same number of atoms.
D) / The pressure of a gas sample varies inversely with the volume.
E) / All gas samples of the same volume at STP contain the same number of molecules.

3. A flexible container is charged with 51.00L of gas at 368. Under conditions of constant pressure and moles of gas, what is the volume of the gas when the temperature is tripled?

A) / 153 L
B) / 17.0 L
C) / 0.0588 L
D) / 51 L
E) / 0.850 L

4. A 22.4-L sample of nitrogen at 3.65atm and 22°C is simultaneously expanded to 57.4L and heated to 38°C. What is the new pressure of the gas?

A) / 2.46 atm
B) / 1.50 atm
C) / 204 atm
D) / 334 atm
E) / 1.35 atm

5. Equal volumes of propane, C3H8, and carbon monoxide, CO, at the same temperature and pressure have the same

A) / chemical properties.
B) / number of atoms.
C) / average molecular speed.
D) / density.
E) / number of molecules.

6. The behavior of PH3(g) is most likely to approach ideal behavior at

A) / 1.0 atm and 100°C.
B) / 0.10 atm and –100°C.
C) / 10 atm and 100°C.
D) / 0.10 atm and 100°C.
E) / 1.0 atm and 0°C.

7. A gas occupies a volume of 2.00L at 860mmHg and 30.0°C. Which of the following mathematical expressions will yield its volume at STP?

A) /
B) /
C) /
D) /
E) /

8. What is the pressure of a 59.6-L gas sample containing 3.01mol of gas at 44.9°C? (R=0.0821L•atm/(K•mol), 1 atm=760 torr)

A) / 1.41  102 mmHg
B) / 1.73  10–3 mmHg
C) / 1.32 mmHg
D) / 1.00  103 mmHg
E) / 5.77  102 mmHg

9. The density of O2 gas at 4°C and 1.57atm is

A) / 153 g/L.
B) / 35.2 g/L.
C) / 2.21 g/L.
D) / 68.8 g/mL.
E) / 0.453 g/L.

10. An unknown gaseous hydrocarbon consists of 85.63% carbon by mass. A 0.335-g sample of the gas occupies a volume of 0.107L at STP. What is the identity of the gas?

A) / C5H10
B) / C6H12
C) / C7H14
D) / CH2
E) / C4H8

11. A 22.4 L high pressure reaction vessel is charged with 0.3910 mol of iron powder and 1.20 atm of oxygen gas at standard temperature. On heating, the iron and oxygen react according to the balanced reaction below.

4Fe(s) + 3O2(g)  2Fe2O3(s)

After the reaction vessel is cooled, and assuming the reaction goes to completion, what pressure of oxygen remains?

A) / 0.903 atm
B) / 1.196 atm
C) / 0.675 atm
D) / 0.293 atm
E) / 0.196 atm

12. In which of the following reactions will the pressure increase upon completion of the reaction at constant temperature?

A) / C(s) + O2(g)  CO2(g)
B) / 2NO(g) + O2(g)  2NO2(g)
C) / C2H6O(l) + 3O2(g)  2CO2(g) + 3H2O(l)
D) / 4NH3(g) + 5O2(g)  4NO(g) + 6H2O(g)
E) / Cl2(g) + 3F2(g) 2ClF3(g)

13. A vessel with a volume of 32.5L contains 2.80g of nitrogen gas, 0.403g of hydrogen gas, and 79.9g of argon gas. At 25°C, what is the pressure in the vessel?

A) / 63 atm
B) / 256.2 atm
C) / 1.73 atm
D) / 0.145 atm
E) / 0.87 atm

14. In a mixture of argon and hydrogen, occupying a volume of 1.66L at 910.0mmHg and 54.9oC, it is found that the total mass of the sample is 1.13g. What is the partial pressure of argon?

A) / 455 mmHg
B) / 319 mmHg
C) / 866 mmHg
D) / 591 mmHg
E) / 43.7 mmHg

15. The partial pressures of CH4, N2, and O2 in a sample of gas were found to be 155mmHg, 476mmHg, and 669mmHg, respectively. What is the mole fraction of nitrogen?

A) / 20.9
B) / 0.880
C) / 0.515
D) / 0.410
E) / 0.366

16. A sample of oxygen is collected over water at a total pressure of 690.7mmHg at 19°C. The vapor pressure of water at 19°C is 16.5mmHg. The partial pressure of the O2 is

A) / 0.9305 atm.
B) / 0.9349 atm.
C) / 0.9088 atm.
D) / 1.070 atm.
E) / 0.8871 atm.

17. Which of the following is included as a postulate in the kinetic molecular theory of an ideal gas?

A) / Collisions between molecules are all elastic.
B) / All molecules move randomly in zigzag directions.
C) / The distance between gas molecules is small compared with the size of the molecule.
D) / All the molecules have the same velocity.
E) / In an average collision between molecules, both molecules have the same kinetic energy.

18. Molecular speed distributions for a gas at two different temperatures are shown below. Which of the following graphs correctly describes the distributions at the two temperatures, where T2T1? NOTE: The small vertical lines indicate average speed.

A) /
B) /
C) /
D) /
E) / none of the above

19. Calculate the root-mean-square velocity for the O2 molecules in a sample of O2 gas at 24.3°C. (R=8.3145J/Kmol)

A) / 15.22 m/s
B) / 137.6 m/s
C) / 277.9 m/s
D) / 481.4 m/s
E) / 9.167  1026 m/s

20. The internal energy of a substance is defined as

A) / the potential energy of all particles which make up the substance.
B) / the kinetic energy of all particles which make up the substance.
C) / the sum of the potential and kinetic energy of all particles which make up the substance.
D) / the thermal energy of all particles which make up the substance.
E) / the chemical energy of all particles which make up the substance.

21. At constant pressure, the sign of q for the process CO2(s) CO2(g) is expected to be

A) / positive, and the process is exothermic.
B) / negative, and the process is exothermic.
C) / impossible to predict.
D) / positive, and the process is endothermic.
E) / negative, and the process is endothermic.

22. H2 and F2 react according to the following equation, forming HF.

H2(g) + F2(g)  2HF(g); H° = –271 kJ

If H2(g) and F2(g) were mixed in a thermally insulated vessel, the reaction that occurred would be

A) / endothermic, and the temperature of the reaction system would fall.
B) / We could not tell unless the original and final temperatures were given.
C) / exothermic, and the temperature of the reaction system would fall.
D) / exothermic, and the temperature of the reaction system would rise.
E) / endothermic, and the temperature of the reaction system would rise.

23. Which of the following statements is incorrect concerning the thermochemical equation below?

2SO3(g)  2SO2(g) + O2(g); H° = 198 kJ

A) / The enthalpy of the reactants exceeds that of the products.
B) / The reaction is endothermic.
C) / For the reaction 2SO2(g) + O2(g)  2SO3(g), H° = –198 kJ.
D) / The external pressure is 1 atm.
E) / For every mole of SO3(g) consumed, 99 kJ of heat at constant pressure is consumed as well.

24. What is the quantity of heat evolved at constant pressure when 60.3g H2O(l) is formed from the combustion of H2(g) and O2(g)?

H2(g)+O2(g)H2O(l); H°=–285.8kJ

A) / 1.17  10–2 kJ
B) / 285.8 kJ
C) / 1.72  104 kJ
D) / 85.4 kJ
E) / 9.57  102 kJ

25. The reaction of iron with hydrochloric acid is represented by the following thermochemical equation.

Fe(s)+2HCl(aq)FeCl2(aq)+H2(g); H°=–87.9kJ

If, in a particular experiment, 7.36kJ of heat was released at constant pressure, what volume of H2(g), measured at STP, was produced? (R=0.0821L•atm/(K•mol))

A) / 2.92 102 L
B) / 2.05 L
C) / 22.4 L
D) / 2.68 102 L
E) / 1.88 L

26. The quantity of heat required to raise the temperature of a sample of a substance by 1°C is the sample’s

A) / work.
B) / calorimetry.
C) / heat capacity.
D) / specific heat.
E) / enthalpy.

27. The specific heat capacity of copper is 0.384 J/gC. What is the molar specific heat capacity of this substance? The molar mass of copper is 63.54 g/mol.

A) / 24.4 J/molC
B) / 0.00604 J/molC
C) / 165 J/molC
D) / 0.384 J/molC
E) / 2.60 J/molC

28. How much heat is gained by copper when 51.8g of copper is warmed from 15.5°C to 76.4°C? The specific heat of copper is 0.385J/(g·°C).

A) / 3.09  102 J
B) / 29.41 J
C) / 23.45 J
D) / 1.21  103 J
E) / 1.52  103 J

29. Pb(s) + PbO2(s) + 2H2SO4(l)  2PbSO4(s) + 2H2O(l); H° = –509.2 kJ

SO3(g) + H2O(l)  H2SO4(l); H° = –130. kJ

determineH° for the following thermochemical equation.

Pb(s) + PbO2(s) + 2SO3(g) 2PbSO4(s)

A) / 3.77 103 kJ
B) / –521 kJ
C) / –3.77  103 kJ
D) / –639 kJ
E) / –769 kJ

30. Using the following data, calculate the standard enthalpy of reaction for the coal gasification process 2C(s) + 2H2O(g)  CH4(g) + CO2(g).

C(s) + H2O(g)  CO(g) + H2(g); H° = +131.3 kJ

CO(g) + H2O(g)  CO2(g) + H2(g); H° = –41.2 kJ

CO(g) + 3H2(g)  CH4(g) + H2O(g); H° = –206.1 kJ

A) / –116.0 kJ
B) / 378.6 kJ
C) / +15.3 kJ
D) / –157.2 kJ
E) / –378.6 kJ

31. What is H° for the following phase change?

KCl(s) KCl(l)

Substance / H°f (kJ/mol)
KCl(s) / –436.68
KCl(l) / –421.79
A) / 858.47 kJ
B) / 14.89 kJ
C) / –858.47 kJ
D) / –14.89 kJ
E) / 0 kJ

32. Calculate the change in enthalpy when 52.0 g of solid chromium at 25°C and 1 atm pressure is oxidized. (H°f for Cr2O3(s) is –1135 kJ/mol.)

4Cr(s) + 3O2(g)  2Cr2O3(s)

A) / –1135 kJ
B) / –284 kJ
C) / –568 kJ
D) / +1135 kJ
E) / +568 kJ

33. Which of the following compounds is a nonelectrolyte?

A)NaOHD)KF

B)HNO3E)CH3COOH (acetic acid)

C)C2H6O(ethanol)

34. Identify the major ionic species present in an aqueous solution of Na2CO3.

A)Na2+, CO32–D)Na+, C+, O2–

B)Na2+, C2 –, O3E)Na+, CO32–

C)Na+, C4+, O32–

35. Based on the solubility rules, which one of the following compounds should be insoluble in water?

A) CaCO3 B) (NH4)2CO3 C) Na2CO3 D) K2CO3 E) KNO3

36. Based on the solubility rules, which one of the following should be soluble in water?

A) Hg2Cl2 B) Na2S C) Ag2CO3 D) Ag2S E) BaSO4

37. Based on the solubility rules, which of the following will occur if solutions of CuSO4(aq) and BaCl2(aq) are mixed?

A)CuCl2 will precipitate; Ba2+ and SO42– are spectator ions.

B)CuSO4 will precipitate; Ba2+ and Cl– are spectator ions.

C)BaSO4 will precipitate; Cu2+ and Cl– are spectator ions.

D)BaCl2 will precipitate; Cu2+ and SO42– are spectator ions.

E)No precipitate will form.

38. The oxidation number of S in K2SO4 is

A) +6 B) +4 C) +2 D) –1 E) None of the above.

39. Which of the following equations does not represent an oxidation-reduction reaction?

A)3Al + 6HCl  3H2 + AlCl3

B)2H2O  2H2 + O2

C)2NaCl + Pb(NO3)2 PbCl2 + 3NaNO3

D)2NaI + Br2 2NaBr + I2

E)Cu(NO3)2 + Zn  Zn(NO3)2 + Cu

40. Identify the reducing agent in the following chemical reaction.

Cd + NiO2 + 2H2O Cd(OH)2 + Ni(OH)2

A) Cd B) NiO2 C) H2O D) Cd(OH)2 E) Ni(OH)2

Answer