How concentration affects the rate of reaction between Hydrochloric Acid and Sodium Thiosulphate

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How concentration affects the rate of reaction between Hydrochloric Acid and Sodium Thiosulphate

Chemistry Coursework

How Concentration Affects a Reaction

Aim:

The aim of this experiment is to find out how concentration affects the rate of reaction between Hydrochloric Acid and Sodium
Thiosulphate.

Introduction:

This experiment will be carried out by drawing a cross on a piece of paper and mixing hydrochloric acid and sodium thiosulphate together to see if the cross disappears. The concentration of hydrochloric acid would change every reaction to show that concentration effects a reaction. The time in which the cross took to disappear would be recorded as well as the temperature at the start and end of the reaction, the concentration
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The sunlight could affect the speed therefore the experiment will take place in the shade, so that temperature shouldn't change the reaction speed, we will check by using a thermometer. Also the same amount of hydrochloric acid and sodium thiosulphate will be mixed each time so that the concentration changes will affect the same amount of hydrochloric acid and sodium thiosulphate. The concentration of the hydrochloric acid will be changing each time to test if it speeds up a reaction. The speed for the light intensity to drop by 10% will be measured after each attempt so that the affects of concentration changes can be recorded. Each concentration will be tested three times and an average will be worked out, to see if there were any anomalies within the experiment. If one result is out of line with the others then that will be easily identified using graphs and tables. The concentration has been picked so that there is a range from 0.25M to 2M, at intervals of 0.5M, 1M, 1.25M and 1.5M.

Prediction:

I predict that the higher the concentration the faster the reaction will take place meaning the light intensity will drop by 10%. This is because the more concentrated the hydrochloric acid is the more particles there are to collide, therefore more effective collisions to break old bonds and make new bonds. 0.25M concentration would be the slowest reaction and 2M would be the
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