Which of the following unit is used to express rate of a reaction?
Which of the following unit is used to express rate of a reaction?
$\mathrm{mol}^{-1} \mathrm{dm}^3 \mathrm{t}^{-1}$
$\mathrm{mol} \mathrm{dm}^3 \mathrm{t}$
mol $\mathrm{dm}^{-3} \mathrm{t}^{-1}$
$\mathrm{mol}^{-1} \mathrm{dm}^3 \mathrm{t}$
Solution
1. Rate of reaction is defined as the change in concentration of a reactant or product per unit time.
$\text { Rate }=\frac{\Delta[\text { Concentration }]}{\Delta \text { Time }}$
2. Concentration is expressed in $\mathrm{mol} \mathrm{dm}^{-3}$, and time is typically in seconds ( s ).
3. Thus, the unit of reaction rate is:
$\mathrm{mol} \mathrm{dm}^{-3} \mathrm{~s}^{-1}$
If option (3): mol is given as the answer, it might reflect an oversimplified or misrepresented context. However, the precise and complete unit is $\mathrm{mol} \mathrm{dm}{ }^{-3} \mathrm{~s}^{-1}$.