16. Kinetics II

Question 1

Define what is meant by the rate of reaction

Answer 1

The change in concentration/ amount of reactant or product produced per unit time

Question 2

Give the techniques to measure rate of reaction

Answer 2

Electrical conductivity - - During a reaction there may be a change in the number of ions
which will affect the level of conductivity.

Measurement of change of mass

Measurement of change in volume of a gas - gas syringe

Titration - Small samples are removed from the reaction mixture, quenched (which stops the reaction) and the titrated with a suitable reagent.

Colorimetry - A common reaction is between propanone and iodine. The reaction goes from brown to colourless

Measurement of optical activity

The change in pH of a reaction

Question 3

Give the rate equation

Answer 3

Rate (mol dm-3) = k[A]^m[B]^n

K = rate constant which is fixed at a particular temperature. If the temperature changes so does the rate constant.
- The larger the value of ‘k’ the faster the rate of reaction
m and n = orders

Question 4

Give the different orders of a rate reaction

Answer 4

0 order - The concentration of A has no effect on the rate of reaction

1st order - The rate of reaction is directly proportional to A

2nd order - The rate of reaction is proportional to A squared