Question

The equilibrium constant of a reaction at $298K$ and $1000K$ is $5\times {10}^{-3}$ and $2\times {10}^{-3}$ respectively. The $\Delta H$ for the reaction is:

• A. positive
• B. negative
• C. either positive or negative
• D. zero

Answer 1

The correct option is B negative

With the increase in temperature from $298K$ to $1000K$, the value of the equilibrium constant decreases from $5\times {10}^{-3}$ to $2\times {10}^{-3}$.

Thus, as the temperature increases, the equilibrium shifts to the left direction. This is possible for an exothermic reaction.

Thus, the reaction is an exothermic reaction having a negative value of enthalpy change.