Maths for A Level Chemistry - updated edition

An experiment to ϐind the rate of decomposition of H 2 O 2 gave the following results Time/s 0 50 100 150 200 250 300 Volume O 2 /cm 3 0 5.0 10.0 14.8 19.0 22.5 25.0 Plot these results and determine the initial rate of production of oxygen from your plot. Answer The points are plotted. Make sure that you label both axes and include the units. Notice the correct way that this is done. First include the name of the quantity and then use a / symbol and write the units after this. So on the y- axis we would use Volume/cm 3 When you plot the points you will notice that not all the points lie on a straight line. They are in an almost straight line initially but start to bend. Hence, we need to draw a straight line up to about 200 s and then a smooth curve after that. As the start of the graph is a straight line we can say that the gradient and hence the rate of change of O 2 is constant. 0 50 100 150 200 250 300 Time/s Volume O 2 /cm 3 25 20 15 10 5 0 To ϐind the gradient, we need to draw a triangle in the straight section of the graph. Mathematics for Chemistry 42