Rates

Change of concentration over time

The effect the concentration of the reactant has on the rate

The sum (addition) of the orders with respect to each reactant.

A proportional constant, which multiplies with the concentration and orders to equal the rate.

The time for half of the reactant to be used up.

The slowest step in the series of steps which make a reaction

Rate = k [A]^m {B]^n

When the concentration of a reactant has no effect on the rate {A]^0

The rate depends on the concentration raised to the power of one, so if the concentration is tripled the rate is also tripled. [A]^1

The rate depends on the concentration raised to the power of two, so if the concentration is tripled the rate increases by a factor of 9. [A]^2

Put the units of the rate and divide it by the units of the concentration, if it is second order you divide it by the units squared

Divide the rate by the concentration, if it is a second order reaction you square the concentration

You compare the initial rate at various concentrations and see how much the rate changes, i.e. does it double or is it squared.

Colorimeter, mass loss, gas collected

Straight light with a negative gradient

Curve down with decreasing gradient over time, less steep then second

Curve, gradient decreases over time, more steep then first

First order reactions have a constant half life

Draw a tangent at a particular concentration, the gradient of the tangent is equal to the rate.

K = ln2 / half life

Horizontal straight line with no gradient, y-intercept is K. Reaction rate does not change with concentration

Straight line that goes through the origin. Rate constant an be determined by measuring the gradient

An upward curve with an increasing gradient. Rate constant can be determined by drawing a second graph of the rate against concentration squared. This results in a straight line going through the origins, the gradient equals the rate constant

The rate equation only includes reacting species involved in the rate determining step. The orders in the rate equation match the number of species involved in the rate determining step.