Rates of Reaction

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Rates of Reaction.

Sodium Thiosulphate + Hydrochloric Acid Sulphur + Sulphur dioxide + Sodium chloride + Water

Results:

Temperature (Celsius) Time (in Seconds)

1st exp. 2nd exp. Average Rate (S-1)

21 180 200 190 5.3x10-3

32 135 125 130 7.7x10-3

41 46 48 49 20x10-3

50 31 33 32 31.25x10-3

60 26 24 25 40x10-3

72 12 11 1.5 86.9x10-3

83 5 7 6 166.6x10-3

Conclusion:

The higher the temperature, the faster the reaction takes place; the quicker the rate of reaction. As the temperature increase 10 0C the time taken for the sodium thiosulphate and hydrochloric acid to react will half. This can be seen looking at the red lines of interpretation one the first graph. Looking at the second graph we can see that for every 10 0C increase the reaction rate doubles. Had I made a prediction for this experiment I would have probably anticipated that when you double the temperature the reaction rate halves, as I can see from looking at my graphs this does not happen. The reason the rate of reaction does not half when you double the temperature can be explained by collision theory. To explain the collision theory you first have to understand what causes any reaction to start. For different chemicals to react the different molecules have to collide with enough energy. This initial energy is known as the activation energy. This is the energy needed to break the existing bonds and then form new one. Heating a reaction means particles speed up and move faster. Because they are moving faster they collide more often and so the reaction happens twice as fast for every 100C rise in temperature; the rate of reaction is increased. During this reaction the energy changes are: Potential chemical energy --> Kinetic energy --> heat/sound wasted energy.
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Extra Research

With the increase of temperature the number of collisions per second does increase however this is only a small contributing factor to the increased rate of reaction that I observed. The reason that the reaction rate increases can be explained by looking at the activation energy of the moving molecules and chemical kinetics.

In order for any chemical change to take place between two chemicals, where two molecules combined in a single step to form a new molecule, old bolds must be broken and new bonds formed. For both bond destruction and also ...

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