In an enzyme-catalysed reaction, the potential energy of the substrates at the start of the reaction is 50 kJ, and the maximum potential energy reached along the reaction pathway, with the enzyme present, is 68 kJ. Calculate the activation energy of this catalysed reaction, in kJ.
Model answer
18 kJ
Also accepted: 18kJ, 18
Explanation
Activation energy is the difference between the maximum potential energy reached during the reaction and the initial potential energy of the substrates: 68 kJ minus 50 kJ equals 18 kJ.
Derived from ZIMSEC Biology Paper 2, June 2017, Q2