1. Integrated Rate Law

2. Method of Initial Rates
Integrated Rate Law:
A reaction is followed for an extended
period of time.
Method of Initial Rates
A reaction is followed for only the
first few moments of the reaction.

3. Advantages of the Method of Initial Rate:
1. Useful when a reaction is reversible.
The reverse reaction won’t significantly
contribute to the first few moments
of the reaction.
2. Useful for very fast or very
slow reactions.

4. Advantages of the Integrated Rate Method:
1. Useful for moderate length reaction.
2. Doesn’t require multiple experiments
to determine the order of the
reaction.

5. Common Uses of the Method of Initial Rates:
1. To determine the order of the
reaction.
2. Find the rate constant, k .

6. Common Uses of the Method of Integrated Rate Laws:
1. To determine the order of the
reaction.
2. Find the rate constant, k .
3. To determine the concentration
at a certain time.
4. To determine at what time a
certain concentration will be
reached.

7. Concentration of D over Time
This is the raw data
collected during the
experiment
Start your analysis by
graphing [D] v. Time

10. The data do not form a straight line. The R2 value only has one “9”.
This reaction is NOT
zero order!

11. Next, convert your raw data to natural logs
and graph ln[D] v. time

14. R2 = 1.0
The data DO form a
straight line.
The R2 value is 1.0.
This reaction is
first order.

15. Normally, when you get a straight line
you stop making graphs.
For teaching purposes, let’s go ahead
and look at the third kind of graph:
1/[D] v. time