Rate determining step + Arrhenius equation

What is the rate determining step of a reaction?

• the slowest step of the reaction

• overall rate of reaction is dependant on this step

What species appear in the rate equation of a reaction?

species involved in the steps up to an including the RDS

What is the Arrhenius equation?

shows the link between the rate constant, activation energy and temperature

What does k stand for the Arrhenius equation?

rate constant

What does A stand for in the Arrhenius equation?

Arrhenius constant (same units as k)

What does e stand for in the Arrhenius equation?

button on calc

What does Ea stand for in the Arrhenius equation?

activation energy

What are the units for activation energy in the Arrhenius equation?

Jmol^-1

What is R in the Arrhenius equation?

gas constant (8.31 Jmol^-1K^-1)

What does T stand for in the Arrhenius equation and what are its units?

temperature - Kelvin

What is the form of the Arrhenius equation which does not have the power?

ln k = ln A - Ea/RT

How can the Arrhenius equation be linked to the graphical equation y = mx + c?

ln k = y

-Ea/R = m

1/T = x

ln A = c

What is the gradient of a graph showing ln k against 1/T ?

gradient = -Ea/R

How can the gradient of a ln k and 1/T graph be used to calculate Ea?

• work out gradient of the line

• gradient = -Ea/R

• gradient x -R = Ea in Jmol^-1

• Ea often wanted in kJmol^-1