To investigate how changing the temperature affects the rate of reaction between sodium thiosulphate and hydrochloric acid.

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Chemistry Coursework: rate of reaction                 Tom Burgess

Aim: To investigate how changing the temperature affects the rate of reaction between sodium thiosulphate and hydrochloric acid.

Background information: The rate of reaction is the formation of a product during a chemical reaction. It is measured by dividing 1 by the time taken for the reaction to take place. There is five factors which affect the rate of a reaction, according to the collision theory of reacting particles: temperature, concentration, pressure (in gases), surface are, and catalysts.

The explanation for a chemical reaction involves the idea of collision. For particles to react they have to collide with enough energy, so not all collisions are successful. To speed up a reaction you must increase the number of collisions and the energy that the collisions have

Small surface area:

Larger surface area:

Formula:

Preliminary experiment: In class we did a background investigation where instead of changing the temperature, which is what I am doing in this investigation, we changed the concentration. A diagram of the apparatus we used is below.

We diluted the thiosulphate solution and timed how long it took for the cross to disappear.

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The results we obtained from the preliminary experiment were.

From the preliminary experiment I can conclude that the speed of the reaction becomes slower as less thiosulphate is added and more water is added. This happens because the solution becomes diluted making the amount of molecules colliding into each other smaller. Therefore it takes longer for the collisions to occur.

If the volume of thiosulphate is increased and the volume of water is decreased, the reactions would be quicker also. There would be more collisions, as the solution would be stronger.  

Apparatus:

 

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