Rates of Reaction : sodium chloride + sulphur + sulphur dioxide +

... or each concentration as other groups needed to use the computer. However because the computer is very accurate and because I also took results from another group, this will not pose too great a problem

Conclusions Before I can represent my data in graph form and then test my prediction, I have to look at the way the data is laid out. I predicted that both variables would be proportional. This implies that as temperature goes up, time taken goes down. However because reaction time goes down, reaction rate is actually increasing. The best way therefore to represent the results in graph form is to draw a graph of concentration/temperature against the reciprocal of the time taken.

Graph 1 shows concentration against the reciprocal of the time. However it is clear that it is not a straight line graph but rather a curve, gradually getting steeper as molarity increases. It is clear that my prediction was wrong and that the graph is not proportional. I can further test this by running my results through the formula for proportionality.

X' = XY' / Y

so

X' = (0.056 x 60) / 20 = 0.168

If my prediction was correct the reciprocal of time taken for 60% concentration should be 0.168. In fact it is 0.09. The slow growth of the graph followed by a massive increase can be explained by looking at activation energy. All of the reactions happened at room temperature (about 210C). Clearly this energy was only enough to push some of the particles beyond their activation energy. However because the reaction is exothermic it gives out energy and this energy pushes more particles to activation energy and these in turn release more heat. More particles of HCI available to reaction with the sodium thiosulphate means more heat given out and more particles being pushed t ...