Question

Unit of rate constant ‘k’ for a second order reaction is:

• A. s$^{-1}$
• B. mol L$^{-1}$ s$^{-1}$
• C. mol$^{-1}$ L s$^{-1}$
• D. mol$^{-2}$ L s$^{-1}$

Hint:

Always derive rate constant units by balancing rate law dimensions.

Answer 1

The Correct Option is C

For a second-order reaction, the unit of 'k' is determined from the rate law: Rate = k[A]$^2$. Thus, the unit is (mol L$^{-1}$ s$^{-1}$)/(mol$^2$ L$^{-2}$) which simplifies to mol$^{-1}$ L s$^{-1}$.