The aim of this investigation is to find out how the rates of reaction between sodium thiosulphate and hydrochloric acid are affected by changing the concentrations of the reactants.

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Rates of Reaction

                        By Sam Cunningham

The aim of this investigation is to find out how the rates of reaction between sodium thiosulphate and hydrochloric acid are affected by changing the concentrations of the reactants.

Introduction

I am going to investigate the rates of reaction and the effect different variables have in them. The rate of reaction is the speed of the reaction that takes place; it is measured by dividing 1 by the time taken for the reaction to happen. The variables I am going to look at are in accordance with the collision theory of reacting particles; the concentration of the solution, the surface area of the solid particles, temperature, pressure of the gasses and catalysts. I have decided to investigate the effect of the concentration, and experiment to find out the possible effect it will have on the rate of reaction as it is proves to be most accurate as I have found out form my preliminary. The non variable in this experiment which is hydrochloric acid, it will not differ or change but simply stay at a constant 10cm3.

Dealing with temperatures is a tricky option to consider in the first place as the time allowed to experiment wasn’t a great deal. Also dealing with temperatures is a difficult task, particularly when you have to keep high temperatures. I am not working with any solids or gasses so it is easy to work with solutions. Likewise a catalyst complicates things, and if undertaken incorrectly, these errors will alter the results and not follow a pattern which will be displayed in a graph.

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The task, to investigate the rates of reaction, I going to need something more to control it, to slow or speed up; I am going to use water as this dilutes the hydrochloric acid and as it will be demonstrated in a graph, it will hope to prove it speeding and slowing the reaction.

Sodium Thiosulphate reacts with hydrochloric acid to form a yellow
precipitate. The word equation for this is:
 

Task Equation:
Sodium Thiosulphate + Hydrochloric acid = Sodium Chloride + Sulphur +
Water

The chemical equation for this is:

Na₂ S₂ O₃ + 2HCL→ SO₂+S+H₂O+2Na 

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