Question

What is the unit of the reaction rate?

(a) mol dm^-3s^-1

(b) mol dm s

(c) mol dm^-3 s

(d) mol^-1 dm s^-1

This question was addressed to me in semester exam.

Enquiry is from Concentration Gradients and Reaction Rates in Solid Catalysts topic in division Heterogenous Reactions of Bioprocess Engineering

Answer 1

The correct answer is:

(a) mol dm^-3 s^-1

Explanation: The reaction rate is the change in the concentration of a reactant or product per unit time. In a typical reaction, the rate is given by the change in concentration (measured in moles per liter or mol/dm³) over time (measured in seconds, s). Therefore, the units of reaction rate are:

rate=Δ[concentration]Δt=mol/dm3s=mol dm−3s−1\text{rate} = \frac{\Delta [\text{concentration}]}{\Delta t} = \frac{\text{mol/dm}^3}{\text{s}} = \text{mol dm}^{-3} \text{s}^{-1}rate=ΔtΔ[concentration]​=smol/dm3​=mol dm−3s−1

This unit reflects how fast the concentration of a species changes in a reaction with respect to time.