Energy changes - Jamb Chemistry Past Questions and Answers

Question 11:

• JAMB 1983

In the reactions
(I) H₂ (g) + 1/2O₂(g) → H₂O(l); ∆H = -286 KJ
(II) C(s) + O₂g) → CO₂ (g); ∆H = -406 KJ the equations imply that

A. More heat is absorbed in (l)
B. More heat is absorbed in (ll)
C. Less heat is evolved in (l)
D. Reaction (ll) proceeds faster than (l)
E. Reaction (l) proceeds faster than (ll)

Question 12:

• JAMB 1983

When sodium dioxonitrate (lll) (NaNO₂) dissolves in water, ∆H is positive. The process of dissolution is

A. Exothermic
B. Endothermic
C. Isothermal
D. Isomeric
E. Hygroscopic

Question 13:

• JAMB 1983

The equilibrium reaction between copper (l) chloride and chlorine at 25^oC and 1 atmosphere is represented by the equation:
2CuCl +Cl₂ ⇌ 2 CuCl₂ ∆H = - 166 KJ. Which of the following statements is TRUE for the reaction, pressure remaining constant?

A. More CuCl is formed at 40^oC
B. More CuCl₂ is formed at 10^oC
C. Less CuCl₂ is formed at 10^oC
D. There is no change in the amount of CuCl₂ formed at 40^oC and10^oC
E. More CuCl is consumed at 40^oC

Question 14:

• JAMB 1984

In dilute solution the heat of the reaction NaOH + HCl = NaCl + H2O is - 57.3kJ. Therefore the heat of the reaction 2NaOH + H₂SO₄ \(\to\) Na₂SO₄ + 2H₂O is

A. + 28.65 kJ
B. - 28.65KJ
C. + 57.3KJ
D. - 114.6 KJ
E. - 229.2 KJ

Question 15:

• JAMB 1984

The diagram above (Fig.3) shows the energy profile for the reaction A + B + = C + D From this diagram, it is clear that the reaction is

A. Spontaneous
B. Isothermal
C. Adiabatic
D. Exothermic
E. Endothermic