Rate Equations: Rate Equations - Arrhenius Equation

Question 1

What is the Arrhenius equation?

Answer 1

• k = Ae^(-Ea/RT)

• k = rate constant
• Ea = activation energy (J mol^-1)
• T = temperature (K)
• R = gas constant (8.31 J K^-1 mol^-1)
• A = Arrhenius constant

Question 2

What does the Arrhenius constant show?

Answer 2

• Shows how rate constant varies with temperature and activation energy

Question 3

Give the rearranged Arrhenius equation to calculate activation energy

Answer 3

• Ea = (ln (A) - ln (k)) x RT

Question 4

How does the rate constant vary with activation energy?

Answer 4

• As activation energy gets bigger, k gets smaller
• A larger activation energy means a slow rate
• If a reaction has a high activation energy, not many reactant particles will have enough energy to react
• Only a few collisions will occur so the rate will be slow

Question 5

Give the rearranged Arrhenius equation to calculate temperature

Answer 5

• T = Ea / R x (ln (A) - ln (k))

Question 6

How does the rate constant vary with the temperature?

Answer 6

• Higher temperatures lead to a higher rate constant
• Higher temperatures mean reactant particles have more kinetic energy and move around faster
• Reactant particles more likely to collide with at least the activation energy, so the rate is higher