Slides in this set
Rate of Reaction
The rate of reaction is determined from experimental results. Reaction rates cannot be
determined from a chemical equation.
Experiments used to obtain rate data include:
The rate of reaction is usually determined by the change in concentration of a reaction species
·Units of rate = mol dm-3 s-1…read more
General Rate Equation
Reaction = A+B C Rate Equation = k[A]m[B]n
In the rate equation, m and n are the orders of reaction with respect to A and B and m plus n will
equal the overall order of reaction.
K is the rate constant (which is only changed by a difference in temperature).
If K has a high value, the rate of reaction will be quick.
If K has a low value, the rate of reaction will be slow.…read more
Orders of Reaction
The reaction: A+B+C Products
The order of the reaction shows how reaction rate is affected by the concentrations of the reactants.
If A had the order of 0, its concentration would not affect the rate of reaction.
If B had the order of 1, its concentration is proportional to the rate of reaction.
· Double concentration = double rate
If C had the order of 2, its concentration is differently proportional to the rate of reaction.
· Double concentration = quadruple rate
· Triple concentration = 9x rate…read more
Rate of Reaction: Initial Rate Method
For the reaction, X + Y Z, a series of experiments can be carried out using different initial
concentrations of the reactants X and Y.
Experiment [X(aq)]/mol dm-3 [Y(aq)]/mol dm-3 [Z(aq)]/mol dm-3s-1
1 1.0 x 10-2 1.0 x 10-2 0.5 x 10-3
2 2.0 x 10-2 1.0 x 10-2 2.0 x 10-3
3 2.0 x 10-2 2.0 x 10-2 4.0 x 10-3
Exp 1 and 2 = [X] x2, Rate x4 [X] = 2nd order
Exp 2 and 3 = [Y] x2, Rate x2 [Y] = 1st order
Rate Equation = k[X]2[Y]
Overall Order = 3…read more
Calculate the Rate Constant
Using the previous data and equation, rate = k[X]2[Y], we can rearrange the equation and put in
the values of the initial rate to calculate K.
1. Rearrange Equation k = rate/[X]2[Y]
2. Put in values from experimental data k = 2.0 x 10-2/[2.0 x 10-3]2[1.0 x 10-2]
3. Calculate answer k = 500 mol-6 dm6 s-1…read more