Investigation to find out if changes in concentration of acid Effect the rate of chemical reactions.

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Investigation to find out if changes in concentration of acid Effect the rate of chemical reactions.

Planning

Introduction

The rate of a reaction is defined as the speed at which the reaction takes place. Many things can affect the rate of reaction. In this coursework I am investigating what Effect the change in acid concentration will have on the rate of reaction.

The reaction between sodium thiosulphate and dilute hydrochloric acid will be used. The concentration of the thiosulphate will be changed; I will do this by adding different amounts of water. The concentration of the acid (hydrochloric) will remain constant.

Table of variables

Planning

Fair test

I have to make sure that this test will be fair. To do this I will keep all the variables constant, other than the concentration of acid. The following variables will be kept constant: The type of acid, the equipment used and the temperature. I will change the concentration of the acid weakening the solution using water. I will start off with pure acid and add more and more water as I go along. I

The ranges I will use for thiosulphate will be from 10cm³ to 50cm³. The volume of the HCL will be constant, at 10 cm³. The volume of Thiosulphate and HCL will always add up to 50cm³.

I will use the same standard each time for judging when the cross on the tile has disappeared. I will make sure that the measuring cylinders for the HCl and thiosulphate will not be mixed up

I will repeat all experiments three times and take an average. By doing this I will increase the level of accuracy, thus I will obtain better results.

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All the above-mentioned factors will make sure that the test is fair.

Sodium Thiosulphate + Hydrochloric Acid

Na²S²O³ (aq) + 2HCl (aq) > 2NaCL + S + H²o + SO²

Prediction:

Before starting my experiment I can predict that the following things will happen. I think that as the concentration of acid is increased, the rate of reaction will also increase. Having said this I could also say that if we double the concentration, we double the number of particles. I looked in my chemistry revision book, which was called GCSE Chemistry Success Guide and was ...

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