The aim of this experiment is to determine whether the concentration of sodium thiosulphate water and hydrochloric acid have any effect on the rate of reaction between the chemicals. I believe that the concentration of sodium thiosulphate has a direct effect on the rate at which the reaction occurs.
Preliminary work.
Having used the internet to Research I have found some useful things on rates of reaction. One of those being heat effects the rate of reaction and also the more the concentrated the substance is the more there is to react and therefore the more violently it will react. I'm not sure about the actual rate at which the substance reacts.
I also found out that particles only react with each other if they have enough energy to force the reaction this is called activation energy. As water has little or no energy I think this will dilute the substance therefore making it harder and take longer to react. I also think that if I were to dilute the substance enough to a point where the energy would be so little that it would not react at all.
Equipment.
Measuring Cylinders (10CM and 50CM), Conical Flask, Paper with X, Beaker of Hydrochloric Acid, Beaker of Sodium Thiosulphate, Stop Clock.
Method.
In order to research what effect the concentration has on the rate of reaction, I will be measuring the time it takes for the reaction to complete, when various different concentrations of sodium thiosulphate are used. I have found from experience that in reactions such as this, the mixture will go cloudy and form a white precipitate and a clear liquid, and so I will be using the turbidity of the mixed chemicals as a measure of how much they have reacted. Therefore, when the mixture becomes opaque, I can assume that the reaction is complete, and I will stop measuring the time. This will give us a value for the rate at which the reaction occurred, which I can compare for different concentrations. The concentration of the sodium thiosulphate is pre-determined and is around 10%, I will vary the volume of sodium thiosulphate compared to the volume of water diluting it, making different concentrations of sodium thiosulphate.
