It has been found that for a chemical reaction with rise in temperature by 9K the rate constant gets doubled. Assuming a reaction to be occurring at 300 K, the value of activation energy is found to be ______ kJ mol–1. [nearest integer] (Given In $10=2.3, \mathrm{R}=8.3 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}, \log 2=0.30$ )