Rates of Reaction Investigation.
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Rates of Reaction Investigation Introduction In this investigation I am going to investigate how fast the chemicals Hydrochloric Acid and Sodium Thiosulphate react. The four main variables that affect rate are: o Temperature - if the reactants are heated/cooled they have more/less energy. If they have more energy there is greater chances of successful collisions meaning the reaction occurs faster. o Concentration - if the solution is more concentrated there are more reactants there is a greater chance of successful collisions. o Surface Area - if one reactant has more surface area there is greater chance of a successful collision as there is more area for the reaction to occur on. o Catalysts - a catalyst is a chemical that speeds up a reaction without changing itself during the reaction. An example of this is an enzyme. In this investigation however I am only going to investigate how concentration affects rate of reaction as the other methods of increasing the rate of reaction are not easily controlled and I do not know of a catalyst that will speed up the reaction.
The higher the amount of water the lower the concentration. Equipment List 100ml Conical Flasks Sodium Thiosulphate Hydrochloric Acid Water Timer Cross on Paper 10cm³ Measuring Cylinder 25cm³ Measuring Cylinder Variables The variables in this experiment are: o Amount of Hydrochloric Acid - the more acid the faster the reaction will take place as there will be more. o Amount of Water - the more water in the solution the less concentrated the acid will be thus slowing down the reaction. o Amount of Sodium Thiosulphate - if there is less sodium thiosulphate there will be not as many molecules for the hydrochloric acid to hit thus reducing the rate of reaction. o Time Taken for reaction to occur I have not included some variable that could not possible be controlled in a classroom environment. Safety As we are using hydrochloric acid we will be wearing safety goggles at all times and also as we are using hydrochloric acid we will be careful to not get any on our hands and if we do we will wash our hands immediately.
Evaluation There is only one anomalous result in my experiment and this is labelled on the graph. This may have occurred due to foreign chemicals entered the solution or we may have measured the Concentration wrong. Therefore I believe that my results are sufficient to support a firm conclusion. This conclusion is that rate of reaction does increase with concentration I believe that my experiment was suitable in the most part however it could have been improved if I had a method of controlling the temperature of the solution constantly so that the reaction speeds up or slows down due to the concentration and not due to the temperature. I could improve accuracy by using mechanical pipettes to measure the liquids. Also I could repeat the experiment further so that I could get even more reliable results. Possible experiments that could be done to further support my theories are perhaps repeat the experiment but this time change the concentration of the sodium sulphate. Also I could do the experiment in a situation where I can control all of the undependable variables, which I could not control in a classroom such as the temperature of the Sodium Thiosulphate/Hydrochloric Acid/Water.
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