Activation energy from Arrhenius data
Ea = R ln(k2/k1) / (1/T1 - 1/T2)
Temperatures must be kelvin and the reciprocal-temperature subtraction order must match the logarithm ratio.
Work it, then mark it
Do each calculation on paper first, then reveal the mark scheme and tick the marks you actually earned — the same way you should mark past papers.
A rate constant increases by a factor of 4.00 when temperature rises from 300 K to 320 K. Calculate Ea. Use R = 8.31 J/K/mol.
Do the calculation on paper first — then mark it.
Where the marks get lost
- Using Celsius temperatures.
- Leaving Ea in J/mol when kJ/mol is requested.
Exam tip: Keep the logarithm ratio and reciprocal-temperature difference in the same high-to-low order so Ea is positive.
Calculations are the most trainable marks in chemistry
They come up every paper and reward a clean method. Send me one you keep dropping marks on — your first lesson is free.