Question

Express the average rate of following reaction in terms of concentrations of reactant and product:

\[\ce{H2_{(g)} + I2_{(g)} -> 2HI_{(g)}}\]

Answer 1

For the reaction 

\[\ce{H2_{(g)} + I2_{(g)} -> 2HI_{(g)}}\]

The average rate in terms of concentration change is:

Rate = \[\ce-{\frac{d[H_{2}]}{dt}}\]

= \[\ce-{\frac{d[I_{2}]}{dt}}\]

= \[\ce{\frac{1}{2}\frac{d[HI]}{dt}}\]

This expression accounts for the stoichiometry of the reaction.