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Rates of reaction.

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Rates of Reaction In this investigation I will mix hydrochloric acid with sodium thiosulphate and heat up the solution to a specific temperature and as this temperature is reached I will measure how many seconds it takes for the cross to disappear. This will show whether the reaction is fast or slow in comparison to the temperatures. If the time has decreased the reaction rate would have increased as this would result in the reaction taking place much quicker. If the time has increased it would suggest that the reaction rate has decreased as it has took longer for the cross to disappear. I will mix the same amount of each acid (20ml). I will also use the same cross. Only one person will be timing the stopwatch, and the same person will also be judging how long it takes for the cross to disappear. The bunsen burner will also always be used with the blue flame. I will also put the thermometer in cold water after each time it has been used to ensure that it gives the correct readings the next time. Also the same beaker will be used, however washed and cleaned each time after the precipitate has formed. ...read more.


The faster the particle, the more kinetic energy it gains and therefore it can reach the activation energy quicker. In short a low temperature slows the reaction rate down. A higher temperature speeds the reaction up. In a cold mixture the reaction will not be quite successful, as the particles will be moving slowly. Collisions with other particles will take place with not much energy and thus resulting in less successful collisions. Whereas, in a hotter mixture the reaction is quicker. The particles move relatively faster, thus colliding with each other more often with more activation energy. As a result more and more collisions will be successful. This means the higher the temperature the faster the rate of reaction. Concentration If the concentration is increased in a solution the more reactant particles there are in the solution. In a reaction where reactants are in a low concentration they are less spread out and thus collisions between particles will be less resulting in fewer success collisions. Where reactants are in a high concentration they are quite close together and thus more collisions take place with a greater number of successful collisions. ...read more.


The fastest reaction was at 60`c. However it would be even faster at a higher temperature. The lower the temperature the slowest the reaction rate. However whilst I was carrying out the experiment for 20`c, I mixed the two chemicals and I never needed to put the beaker on the bunsen burner as it was already 20`c. This low temperature was hard to obtain. If I was to carry this experiment out again I would also experiment on all the other factors affecting the rate of reaction i.e. concentration, surface area etc. As these factors would also make a change to how fast a reaction takes place. I would also try the experiment again but this time with dilute hydrochloric acid as this experiment may give different results than using concentrated acid. I feel the results were quite reliable, however, they may not be too. This is because each person was predicting when the cross had disappeared with the naked eye. There might be mistakes of some seconds here. To overcome this problem only one person should be judging this or maybe the use of a special instrument could be used to overcome this problem which would detect when the cross has disappeared. This would bring further fairness in the experiment. ...read more.

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