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:

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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:

 After having my results (after I will have done the experiment) I will be bale to see ...

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