Question

For an exothermic reaction, increasing temperature will:

• A. Shift the equilibrium toward products
• B. Not affect the equilibrium
• C. Increase activation energy
• D. Shift the equilibrium toward reactants

Hint:

In exothermic reactions, think of heat as a “product.” Adding heat shifts equilibrium to the left, while removing heat shifts it to the right.

Answer 1

The Correct Option is D

According to Le Chatelier’s Principle, if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change.
In the case of an exothermic reaction, heat is evolved during the reaction. It can be written as:
\[ \text{Reactants} \rightarrow \text{Products} + \text{Heat} \]
When we increase the temperature, we are essentially adding more heat to the system. To counteract this additional heat, the system will shift the equilibrium in the reverse direction — that is, toward the reactants, which consume heat.
This shift reduces the amount of products and increases the amount of reactants, thus opposing the disturbance (heat addition).
Hence, for an exothermic reaction, increasing temperature causes the equilibrium to shift toward the reactants.
Other options analyzed:
- (1) Shift the equilibrium toward products — Incorrect, applies to endothermic reactions when temperature increases.
- (2) Not affect the equilibrium — Incorrect, temperature changes always affect equilibrium.
- (3) Increase activation energy — Incorrect, activation energy may change slightly, but it's not the correct focus here.