17: Equilibrium (AHL)

Question 1

How to determine the order of a reaction isolate two experiments

Answer 1

rate = k([A]m)([B]n).

In this example, when [A] doubles, the rate doubles (first-order, for experiments 1 and 3) but when [B] doubles there is no change in the rate of reaction (zero-order, from experiments 3 and 4). The rate expression is rate = k([A]1)([B]0).

Question 2

Using ln(k1/k2)=Ea/R(1/T2−1/T1)
to calculate activation energy

Answer 2

ln(k1/k2)=Ea/R(1/T2−1/T1)

can be utilised to solve for the activation energy given information about the rate constants at two different temperatures.

Ea=R(ln(k1/k2))/(1/T2−1/T1)
Ea=8.31(ln(1.5055.0))/(1/323−1/303)
Ea=146468 J mol−1
Ea=146kJ mol−1