3.1.9 Rate equations Flashcards
What is the rate equation?
Rate = k[A]m [B]n
where m and n are the orders of reaction with respect to reactants A and B and k is the rate constant
What is the rate of reaction?
The change in concentration of a reactant or product with unit time
What are the 3 ways of measuring rate?
- Volume of gas
- Loss in mass
- Time for a set amount of precipitate to form (eg: disappearing cross; iodine cross)
The volume of gas and loss in mass are both continuous method of measuring rate
Why is the rate constant (k) important?
It can be used to compare the rates of different reactions with similar rate equations
What is the shape of a zero order reaction against concentration graph
A straight horizontal line with gradient zero
What is the shape of a first order rate against concentration graph?
A straight line with a positive gradient
What is the shape of a second order rate against concentration graph?
A curve with a steep positive gradient
What is the shape of a first order concentration against time graph?
A curve with a negative gradient and a constant half life
What is the shape of a second order concentration against time graph?
A curve with a steep negative gradient and a fluctuating half life
What are the 3 orders of reaction?
- Zero order (0)
- First order (1)
- Second order (2)
What is the relationship between concentration and rate of a zero order species?
The concentration of the species has no impact on the rate of reaction
What is the relationship between the concentration and rate of reaction of a first order species?
There is a linear relationship between concentration and rate
What is the relationship between concentration and rate of reaction of a second order species?
There is a quadratic relationship between concentration and rate
