The effect of concentration on the rate of reaction of sodium thiosulphate.

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The effect of concentration on the rate of reaction of sodium thiosulphate

        Aim: My aim is find out what effect would hydrochloric acid (the reactor) have on sodium thiosulphate (the reactant).

        Prediction:  The higher concentration of acid, the faster rate of reaction with sodium thiosulphate. My reasoning for this is that the more acid particles in the acidic solution there are, the more particles will collide with the sodium thiosulphate particles, and the more collisions there are, the quicker pace of rate gets. In essence, I predict my results would be, the concentration being directly proportional to the length of time

Equipment: the equipment I will need for this experiment is:

  • Flask
  • Beaker     6
  • Measurement tube     2
  • Timer
  • Pipette    2
  • Funnel
  • Piece of paper with cross

Method: as you can see on the previous page how everything is set out. I will be explaining the method in stages:

  1. Firstly, I will get a measuring tube pour 20cm3 of the acidic solution into it using a pipette, and then pour that into the beaker. I will then pour sodium thiosulphate into the other measuring tube and measure it to also 20cm3. The sodium thiosulphate will then be poured into the flask.
  2. After Which I shall pour the acidic solution from the beaker to the flask using the funnel, so nothing spills. Under the flask I will place a paper with a cross in black ink. Then I will simultaneously start the timer for ten seconds and pour in the acidic solution into the flask.
  3. I will do six different experiments in total, all with different concentrations, and each will be repeated twice to get an accurate average.
  4. Before I do anything I will do some preliminary testing. By this I mean I will do a pre test as I collect the data to see if there is a pattern, I will then put them in a table and then graph. This will then be included into my investigation below:
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Preliminary Results

Preliminary Graph

Explanation: What happens is when both hydrogen and sodium thiosulphate react they release a chemical which starts to make more and more cloudy. So, when the cross isn’t visible by the naked eye anymore (from a clear to cloudy solution) I then stop the timer. This will then give us the time it took for each experiment’s (six in total) reaction to go cloudy. In effect, since I want to work out the rate of reaction, I stopped all the experiments near enough ...

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