The Effect of Sodium Thiosulphate Solution on the Rate of its Reaction with Hydrochloric Acid

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The Effect of Sodium Thiosulphate Solution on the Rate of its Reaction with Hydrochloric Acid

Aim

I shall investigate how the concentration of Sodium thiosulphate

solution affects the rate of its reaction with hydrochloric acid.

I shall add water to the sodium thiosulphate solution to weaken the

concentration so I can see how concentration can affect the rate of

reaction.

I shall add water as that is the only way I can find out how

concentration affects the rate of reaction as I cannot increase

concentration from 1M upwards as I do not have the resources available

to use.

[IMAGE]Prediction

I predict that when I add more water to the sodium thiosulphate

solution, the time it takes for the cross to disappear will lengthen.

[IMAGE]I predict this because, for particles to react they must

collide with each other. If there is a higher concentration of sodium

thiosulphate particles in a given volume there is a higher chance of

the particles colliding together and reacting. This is because they

are so close together. If you weaken the solution, (so there is a much

lower concentration of sodium thiosulphate particles to react with the

hydrochloric acid,) then there is less chance of the particles

colliding and reacting as there are less particles in the given

volume, so the reaction time will slowly lengthen as the concentration

goes down.

[IMAGE]My graphs should hopefully look like this.

Plan

Factors to control

I shall have to control as many aspects of the experiment as possible,

to make it a fair test.

I shall make sure the total volume of the solution stays the same. I

shall do this by reducing the volume of sodium thiosulphate as I add

water, the total volume of the sodium thiosulphate solution and water

will be 50cm3. An example would be having 30cm3 of sodium thiosulphate

and having 20cm3 of water, added together their volume is 50cm3.

I shall do this because if I did not then the total volume would go up
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