The Effect of Concentration on the Reaction between Sodium Thiosulphate and Hydrochloric Acid

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The Effect of Concentration on the Reaction between Sodium Thiosulphate and Hydrochloric Acid

We are given 2md/dm³ of Hydrochloric Acid = 10cm³. We are also given

the measurement of Sodium Thiosulphate solution: 40g/dm³ = 50cm³

The chemical equation for this reaction is:

2Hcl + Na²S²O² 2NaCl + H²O + SO² + S

I am going to investigate the effect of concentration in this

reaction. To do this I will change the volume of 0.1 mol/dm³ of sodium

Thiosulphate. We will keep the amount of Hcl the same, because if we

altar that one it will totally change the results and there would be

no pattern. We learned that if the concentration doubles, the rate

doubles. I will therefore choose the dilute sodium Thiosulphate to

prove this and to see if it affects the rate of the reaction. Besides

concentration I know that catalysts, temperature and surface area also

affect the rate of the reaction. Therefore I think that the less

concentration of sodium Thiosulphate the slower the rate of the

reaction will go. We did preliminary work on this experiment, I took a

conical flask and put 50cm³ of sodium Thiosulphate and added 10cm³ of

Hcl. Under the conical flask I put a white piece of paper and put a

black cross on it. We made sure that our cross was very dark and think

because if it was just a thing cross you might not see it so well and

think it has disappeared even though with a thicker cross you can

still see it. This is how we set it up:

[IMAGE]

As we are trying to find out what happens with different

concentrations I will change (decrease) the amount of sodium

Thiosulphate and add amounts of water to the solution with so that the

concentration differs but the amount of the mixed solutions is still

the same. The amount of hydrochloric acid will stay the same through

the whole experiment.

This is a table to show the volume of sodium Thiosulphate, water and

hydrochloric acid I will use:

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