Ncert Exercises & Solutions

In an exothermic reaction, heat is evolved, and system loses heat to the surrounding. For such system

1. q_p will be negative

2. $∆_{r} H$ will be negative

3. q_p will be positive

4. $∆_{r} H$ wil be positive

(a, b)

Exothermic reactions are those reactions which are accompanied by the evolution of heat.

e.g.,

C (s) + O_{2} (g) \to {CO}_{2} (g) + 393.5 kJ

H_{2} (g) + \frac{1}{2} O_{2} (g) \to H_{2} O (l) + 285.8 kJ

q_{p}

and

∆_{r} H

are negative for an exothermic reaction.