Energy changes - Jamb Chemistry Past Questions and Answers

Question 16:

• JAMB 1985

A certain industrial process is represented by the chemical equation 2A_(g) + B_(g) \(\to\) C_(g) + 3D_(g) \(\Delta\)H = X kJmol^-1. Which of the following conditions will favour the yield of the products?

A. Increase in temperature, decrease in pressure
B. Increase in temperature, increase in pressure
C. Decrease in temperature,increase in pressure
D. Decrease in temperature, decrease in pressure
E. Constant in temperature, increase in pressure

Question 17:

• JAMB 1985

In the reaction H_2(g)O \(\to\) H_2(g) + 1/2O_2(g)
ΔH = -2436000 KJ, which of the following has no effect on the equilibrium position?

A. Adding argon to the system
B. Lowering the temperature
C. Adding hydrogen to the system
D. Decreasing the pressure
E. Increasing the temperature

Question 18:

• JAMB 1985

The energy change (ΔH) for the reaction CO(g) + (1)/(2)O_2(g) → is?
(ΔHi(CO) = -110.4 kJ mol^-) (ΔHi(CO₂) = -393 kJ mol^-)

A. -503.7 kJ
B. +503.7kJ
C. -282.9 kJ
D. +282.9 kJ
E. +393.3 kJ

Question 19:

• JAMB 1985

When marble is heated to about 1473 K, another white solid is obtained which reacts vigorously with water to give an alkaline solution. The solution contains?

A. NaOH
B. KOH
C. Mg(OH)₂
D. Zn(OH)₂
E. Ca(OH)₂

Question 20:

• JAMB 1986

20 cm³ of 1.0 molar NH₄OH solution when neutralized with 20.05cm³ of 0.1 molar HCl liberated -102 joules of heat. Calculate the heat of neutralization of NH₄OH?

A. -51.O KJ mol^-
B. +57.3 KJ mol^-
C. +57.O KJ mol^-
D. +51.0 KJ mol^-