Chemistry rate of reaction coursework

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Chemistry Plan

I am going to produce a piece of coursework investigating the rate of reaction, selecting a variable to see how this affects the rate. The rate of reaction is the rate of loss of a reactant or the rate of formation of a product. The rate is measured by dividing one by the time the reaction took to take place.

There are five factors that affect the rate of reaction:


Concentration (of solution)

Pressure (in gases)

Surface area (of solid reactants)


I have decided to investigate the effect of concentration on the rate of reaction as I feel that it is manageable to measure, will show clear results and is much more practical than the other five variables.

Both the Sodium Thiosulphate and Hydrochloric acid are soluble in water; therefore the concentration of either can be changed. However I have chosen to vary the concentration of the Sodium Thiosulphate as it is available to me in larger amounts and is more practical for my investigation. Also whilst changing the concentration it is vital that all other variables remain consistent throughout the experiment. I will not be using room temperature as I cannot control it and this could cause improbabilities within my investigation. To counter this a water-bath will be used as I can keep the temperature at a constant.

So my aim is to change the concentration in the Sodium Thiosulphate by adding water and taking away Sodium Thiosulphate gradually. The reaction of the experiment will be as follows:

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Sodium Thiosulphate + Hydrochloric Acid

Na2S2O3 (aq) + 2HCL (aq)

For my preliminary investigation I used the variable concentration to give me an idea of the range of results and what to expect in my final investigation. The study produced the following results:

These results have given me an idea of how far the range will vary and that if you do the experiment a number of times the results don’t drastically change.

This is the list of apparatus that I needed to carry ...

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This report is of variable quality. Some aspects are well written but brief and there is not enough mention of the scientific theory behind the investigation. The data is of reasonable quality. There have been specific improvements suggested throughout.