Temperature Dependence and Catalysis
The Arrhenius equation k = A exp(-Ea/RT) describes how rate constants rise with temperature, and a catalyst lowers Ea by providing an alternative path.
What is Temperature Dependence and Catalysis?
The Arrhenius equation k = A exp(-Ea/RT) describes how rate constants rise with temperature, and a catalyst lowers Ea by providing an alternative path.
Key formula / rule: A plot of ln k against 1/T is linear with slope -Ea/R.
Key points
- Compute activation energy from rate constants at two temperatures.
- Explain how a catalyst affects rate without affecting equilibrium.
Common exam trap
Claiming a catalyst increases the yield at equilibrium.
Definitions
- Term
Temperature Dependence and Catalysis
- Meaning
The Arrhenius equation k = A exp(-Ea/RT) describes how rate constants rise with temperature, and a catalyst lowers Ea by providing an alternative path.
- Term
Temperature Dependence and Catalysis — explanation
- Meaning
Only molecules with energy above the activation barrier react, so a modest temperature rise produces a large rate increase. A catalyst changes the path, never the equilibrium position.
Learning objectives
Compute activation energy from rate constants at two temperatures.
Explain how a catalyst affects rate without affecting equilibrium.
Formulae
- Key point
A plot of ln k against 1/T is linear with slope -Ea/R.
- Key point
A catalyst lowers Ea for both forward and reverse reactions equally.
- Key point
Catalysts do not change the value of the equilibrium constant.
Prerequisites
CHE-U1-EK-T1-S2-C1
Common mistakes
Claiming a catalyst increases the yield at equilibrium.
Using Celsius temperature in the Arrhenius expression.
Keywords
Temperature
Dependence
Catalysis
Practice preview
In the Arrhenius equation, k = A exp(-Ea/RT), what does 'A' represent?…
easy
According to the Arrhenius equation, if the temperature of a reaction is increased, what happens to the rate constant (k)?…
medium
Which of the following statements about a catalyst is INCORRECT?…
medium