Energy changes - Jamb Chemistry Past Questions and Answers

Question 46:

• JAMB 2001

When ΔH is negative, a reaction is said to be

A. Ionic
B. Reversible
C. Exothermic
D. Endothermic

Question 47:

• JAMB 2001

NH_3(g) + HCl_(g) → NH₄Cl_(s)
The entropy change in the system above is

A. Negative
B. Indeterminate
C. Positive
D. Zero

Question 48:

• JAMB 2002

When dissolved in water, NaOH flakes show

A. An endothermic change
B. An exothermic change
C. A slow reaction
D. A rapid reaction

Question 49:

• JAMB 2003

CO_(g) + H₂O_(g) → CO_2(g) + H_2(g)
From the reaction above, calculate the standard enthalpies of formation of CO_2(g), H₂O_(g) and CO_(g) in kJ mol^-1 are -394, -242, and -110 respectively.

A. -262 kJ mol^-1
B. -42 kJ mol^-1
C. +42 kJ mol^-1
D. +262 kJ mol^-1

Question 50:

• JAMB 2003

When sugar is dissolved in tea, the reaction is always accomplished by

A. Positive change
B. Negative entropy change
C. No entropy change
D. A minimum entropy change