Question

The reaction between H$_2$ (g) and I$_2$ (g) was carried out in a sealed isothermal chamber. The rate law for the reaction was found to be: \[ \text{Rate} = k[\text{H}_2][\text{I}_2] \] If 1 mole of H$_2$ (g) was added to the reaction chamber and the temperature was kept constant, then predict the change in rate of the reaction and the rate constant.

Hint:

For reactions with multiple reactants, changes in the concentration of one reactant will proportionally affect the reaction rate, depending on the order of reaction.

Answer 1

For this second-order reaction with respect to H$_2$ and I$_2$, the rate of the reaction is proportional to the product of the concentrations of H$_2$ and I$_2$.
When 1 mole of H$_2$ is added, assuming the concentration of I$_2$ remains constant, the rate of reaction will increase proportionally to the increase in the concentration of H$_2$.
Since the temperature is constant, the rate constant (k) remains unchanged.
Thus, the reaction rate increases with increased concentration of H$_2$.