Following reactions

• A reaction stops when all of 1 of the reactants is used up - that reactant is called the limiting reactant
• the amount of reaction formed is directly proportional to the amount of limiting reactant
• e.g. if you 1/2 the amount of limiting reactant the volume of gas produced will also 1/2
• this is because if you add more react there will be more reactant particles to take part in the reaction which means more product particles

For the exam we need to be able to read graphs + tables and answer questions off them. All you do is carefully read the questions and find out what it says in the question on the graph, e.g. How much gas was produced after 15seconds? Find the time axis, find 15, then follow to the line of the graph, then read across to the other axis and you have you answer eg. 47 cm3

As well as this there may be numerous graphs of the same kind of experiment which we need to analyse. If the reactions finish at the same amount of product this shows they all have the same amount of limiting reactant, if one is more steeper to get to that value it just shows that it happened quicker. If a higher amount of product is produced then there was more limiting reactant than in the other experiments.