# F325 ~ The Rate Equation and Orders

**Rates Summary Sheet**

**Key points on rates which you need to know for the F325 exam.**

**(OCR F325)**

- Created by: chloeeyay
- Created on: 06-05-15 17:17

First 223 words of the document:

chloeeyay

The Rate Equation and Orders

Zero Order Reactions

If the order is 0 with respect to a reactant A then rate [A]0

First Order Reactions

1

If the order is 1 with respect to a reactant B then rate [B]

Second Order Reactions

If the order is 2 with respect to a reactant C then rate [C]2

Half Lives

The half-life of a reactant is the time taken for the concentration of the reactant to reduce by

half.

Orders and concentration-time graphs

Zero Order Reactions

Concentration decreases at a constant rate

Half-life decreases with time

First Order Reactions

The first order reaction has a constant half-life

The half-life is the same no matter what the

concentration

Concentration halves in equal time intervals

Second Order Reactions

Concentration decreases rapidly, but the rate of

decrease then slows down

Half-life increases with time

Orders and rate-concentration graphs

Zero Order - rate [A]0

First Order - rate [B]1

Second Order - rate [C]2

The rate is unaffected by If [B] increase by 2, the rate If [C] increases by 3 times

changes in concentration will increase by 2. The rate the rate increases by 32 =9

increases by the same value. times

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