Arrhenius equationAQA A-Level Chemistry: Flashcards

Exam questions on Arrhenius equation

1. A food scientist is studying how quickly a vitamin breaks down in fruit juice during storage. The breakdown is a first order reaction with an activation energy of 85.0 kJ mol⁻¹. Take the gas constant R as 8.31 J K⁻¹ mol⁻¹.
   The storage temperature of the juice rises from 298 K to 308 K. Calculate the factor by which the rate constant increases.2 marks
2. A student measures the rate constant, k, for the hydrolysis of an ester (reaction X) at five temperatures and plots ln k on the vertical axis against 1/T on the horizontal axis, where T is in kelvin. The line is straight, with a gradient of −8.9 × 10³ K. For a second reaction, Y, the equivalent line has a gradient of −5.2 × 10³ K. Take the gas constant R as 8.31 J K⁻¹ mol⁻¹.
   Calculate the activation energy of reaction X in kJ mol⁻¹.2 marks
3. The first order decomposition of compound Z in solution has an Arrhenius constant, A, of 4.5 × 10¹³ s⁻¹ and an activation energy, Ea, of 110 kJ mol⁻¹. Take the gas constant R as 8.31 J K⁻¹ mol⁻¹.
   Calculate the value of the rate constant for the decomposition of Z at 350 K.3 marks