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Question 1

Calculate the change in the molar entropy of a perfect gas when it is compressed isothermally from a pressure of 1 bar to 10 bar

a) +83.1 J K^-1 mol^-1

b) +7.6 J K^-1 mol^-1

c) +19.1 J K^-1 mol^-1

d) +183 kJ K^-1 mol^-1

Question 2

Calculate the change in the standard molar entropy of hydrogen chloride, HCl, gas when it is heated from a temperature of 20°C to 30°C. The standard molar constant-pressure heat capacity of hydrogen chloride is 29.1^-1mol^-1.

a) +11.8 J K^-1 mol^-1

b) +0.976 J K^-1 mol^-1

c) +0.424 J K^-1 mol^-1

d) +29.3 J K^-1 mol^-1

Question 3

The standard enthalpy of sublimation of carbon dioxide is 26.2 kJ K^-1mol^-1 at 298.15 K. Calculate the standard entropy of sublimation at this temperature.

a) 87.9 J K^-1mol^-1

b) 78.1 J K^-1mol^-1

c) 26.2 J K^-1mol^-1

d) 1048 J K^-1mol^-1

Question 4

The boiling temperature of ethylbenzene is 136°C. Use Trouton's rule to estimate the enthalpy of vaporization of ethylbenzene at this temperature.

a) 35 kJ mol^-1

b) 12 kJ mol^-1

c) 23 kJ mol^-1

d) 4.8 kJ mol^-1

Question 5

Calculate the change in entropy when exactly 1 mol of solid iodine, I₂, at a temperature of 360 K is heated at constant pressure to produce liquid iodine at a temperature of 410 K. The constant pressure molar heat capacity of solid iodine is 54.44 J K^-1mol^-1 and of liquid iodine is 80.67J K^-1mol^-1. The melting temperature of iodine is 387 K, and the molar enthalpy of fusion of iodine is 7.87 kJ mol^-1.

a) +8.6 J K^-1 mol^-1

b) +28.9 J K^-1 mol^-1

c) +20.3 J K^-1mol^-1

d) +11.7 J K^-1 mol^-1

Question 6

Which of the following conditions is necessary for a reaction to be spontaneous?

a) ΔS_sur> 0

b) ΔS_sys> 0

c) ΔS_sur+ ΔS_sys> 0

d) ΔS_sur+ ΔS_sys< 0

Question 7

At low temperatures, the heat capacity of solid chlorine, Cl₂, follows the Debye T³ law, C_p_,m= a T³, with a = 1.24 × 10^-3J K^-4mol^-1. Estimate the molar entropy of solid chlorine at 10 K.

a) +1.24 J K mol^-1

b) +0.413 J K^-1mol^-1

c) +6.36 J K^-1mol^-1

d) +4.13 J K mol^-1

Question 8

A hypothetical system consists of 5 molecules and 2 quanta. What is the number of possible arrangements?

a) 21

b) 3

c) 15

d) 2

Question 9

For a spontaneous change in a system at constant temperature and pressure, which of the following statements is true?

a) ΔG < 0

b) ΔG = 0

c) ΔG > 0

d) There is no restriction on the value of ΔG

Question 10

Which of the following statements is always true for a system at equilibrium under conditions of constant temperature and pressure?

a) ΔS > 0

b) ΔG = 0

c) dG = dw'_max

d) ΔG > 0

Oxford University Press, Online Resource Centre, Chapter 04.

Chapter 04

Instructions