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The effect of Concentration on Rates of Reaction

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The effect of Concentration on Rates of Reaction A reaction happens when particles of two different reacting substances collide. Also, a fixed amount of energy known as the Activation energy level must be reached. There are five main factors, which affect the speed at which the Activation energy is reached; this speed is the rate of reaction. The five main factors, which affect the rate of reaction, are: TEMPERATURE, when the temperature is increased there will be more movement within the particles in the substance. Therefore there will be more successful collisions and the rate of reaction will be faster CATALYST, a catalyst is a separate substance, which speeds up the rate of reaction. However the catalyst remains left behind after the reaction has taken place. SURFACE AREA, if a larger piece of a reactant is broken down to simpler pieces, the second reactant will have a larger total area to react with. Therefore a larger surface area results in a faster rate of reaction. CONCENTRATION, when the concentration is increased it means that there are more particles of the reactant in the same area of space. Therefore there will be an increase of successful collision and this will result in a faster rate of reaction. PRESSURE, If the volume where a certain amount of particles exist is reduced, so that the same amount of particles now exist within a smaller volume, there will be more particles ...read more.


I predict that this will happen due to the fact that more Sodium Thiosulphate particles will be present in the same amount of space and the Hydrochloric Acid particles will have more particles to collide with. This will mean the Activation Energy level will be reached faster and the reaction will take place quicker. Therefore I would expect my results to illustrate a graph similar to the one below: (The graph was taken from: www.gcsechemistry.com) The following table shows my results: Sodium Thiosulphate (ml) Water (cm3) Hydrochloric Acid (cm3) Concentration (mol/dm3) % Of Sodium Thiosulphate Time taken for cross to disappear 10 40 5 0.03 20 205 20 30 5 0.06 40 105 30 20 5 0.09 60 68 40 10 5 0.12 80 52 50 0 5 0.15 100 43 In order to try and compare my results with a "perfect" set of results I will have to draw a graph and observe to see if any anomalous results have been produced. This would be very likely and to illustrate this I have drawn a graph: The graph that I drew according to my results is very similar to the graph that I included in my prediction. Therefore I can say that my prediction was correct and that an increase of concentration in the same space results in a faster rate of reaction. ...read more.


This means that there is only little space between these particles and those of the Hydrochloric Acid. Now the particles will Successfully collide more often. The graph produced finally gave a smooth curve to illustrate the statement "The higher the concentration of the Sodium Thiosulphate the quicker the cross will disappear." However at first one anomalous result was achieved. This was for the concentration of 0.12 mol/dm3. The first time given for this concentration level was 53 seconds. This result did not fit the smooth curve and the graph suggested that the result should have been closer to 49 seconds. The second time round I obtained a result of 50 seconds, which fitted the curve and completed the pattern. There could be many reasons for why I gained an anomalous result and the main reason, which I think affected the results, was that it is virtually impossible to stop the stopwatch at the same opaqueness all the time. Therefore repeating some results could improve the accuracy. Also the amount of light in the room is also a major factor. For example, doing one of the results at night and the others in daylight would mean that the experiment is not fair and the cross will disappear quicker in the dark. Therefore using a light meter could be useful, as it would measure the amount of light in the room. ?? ?? ?? ?? OMER ANJUM 10LJ 1 ...read more.

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