Energy changes - Jamb Chemistry Past Questions and Answers

Question 36:

• JAMB 1995

Which of the following processes leads to increase in entropy?

A. Mixing a sample of NaCl and sand
B. Condensation of water vapour
C. Boiling a sample of water
D. Cooling a saturated solution

Question 37:

• JAMB 1995

Use the diagram above to answer this question. The activation energy of the uncatalysed reaction is

A. X
B. X + Y
C. X - Y
D. Y

Question 38:

• JAMB 1997

2SO_2(g) + O_2(g) 2SO₃. In the reaction above, the standard heats of formation of SO_2(g) and SO_3(g) are -297 KJ mol^-1 respectively. The heat change of the reaction is?

A. -99 kJ mol^-
B. -198 kJ mol^-
C. +198 kJ mol^-
D. +683kJ mol^-

Question 39:

• JAMB 1997

One method of driving the position of equilibrium of an endothermic reaction forward is to?

A. Increase temperature at constant pressure
B. Dcrease pressure at constant temperature
C. Cool down the apparatus with water
D. Decreases temperature at constant pressure

Question 40:

• JAMB 1997

(1 /(2) N_2(g) + (1) / (2)O_2(g) → NO_(g) ∆H° 89 KJ mol^-. If the entropy change for the reaction above at 25°C is 11.8 J mol^-, calculate the change in free energy. ∆G°, for the reaction at 25°C?

A. 88.71 KJ
B. 85.48 KJ
C. -204.00 KJ
D. -3427.40 KJ