Unit 10.6.1: Introduction to rates of reaction
Discussion of the meaning of 'Rate' as applied to chemical reactions. Analogy with rate of travel leading to the idea that the average rate is proportional to the reciprocal of the time taken. Stress the danger of using minutes and seconds.
Point out that we must be able to measure a property of one of the components of the reaction that changes in some way (pH, gas volume, colour, mass due to gas loss, conductivity etc).
Another condition is that the rate must not be too slow (oxidation of sugar) nor too fast (hydrogen and oxygen).
During the discussion there could be a variety of experiments that proceed at different rates:
Student follow up
Worksheet on the rate of chemical reactions.
If the oxygen and hydrogen is prepared during the class using gas generator apparatus (conical flask, thistle funnel, delivery tube) then it can serve as a demonstration of gas collection to measure rate and also to prepare the plastic bottle explosion.