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Investigating Rates of Reaction

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Investigating Rates of Reaction HCL(aq)+Na2S203(aq) = 2NaCl(aq)+SO2(g)+S(s)+H2O(l) Effects To investigate the concentration of sodium thiosulphate solution we need to look at the factors affecting rate of reaction. Temperature When the temperature is increased the rate of reaction speeds up. When the temperature decreases the rate of reaction slows down. Concentration When the concentration increases the rate of reaction increases. When the concentration decreases the rate of reaction decreases. Light Intensity When the light intensity increases the rate of reaction increases. When the light intensity decreases the rate of reaction decreases. But light intensity only affects rate or reaction in photosensitive reactions; this reaction is not so therefore light intensity is not a factor we have to consider. Catalyst This provides a different route with a lower activation energy. But in this experiment there is no known catalyst, so we don't need to consider this factor, Surface Area When the surface area increases, the rate of reaction also increases, as there are more particles. But this is only in solids so this also is not a factor we need to consider, as neither reactants are solids. Pressure Neither reactants are gases, so pressure has no effect. ?Both solutions are colourless and water is also colourless so we can't measure colour change. ?SO2 is soluble in water, so we can't measure that. ...read more.


We could keep it fair by doing all the reactions on the same day to make sure the temperature is the same, or monitor the temperatures with a thermometer. We must also keep the volume and concentration of HCL the same throughout because if not the total of solutions will change and the rate of reaction will be affected. If the volume or concentration was greater than the rate of reaction would increase as there are more particles with the required activation energy in a given volume in a given volume as an increased no of successful collision would occur in a given volume in a given amount of time and the test would be unfair, because we are investigating how the concentration of sodium thiosulphate affects the rate of reaction. We must keep the volumes of the solutions the same each time I change the concentration. So if I decrease the amount of sodium thiosulphate then I would need to dilute it more. We must make sure each time the total volume of the substances together is 100. If the volume of all the solutions was higher than previous, then the amount of particles would also be higher and the number with the required activation energy would also increase. Therefore there would be more successful collisions in the volume so the time taken will be lower. ...read more.


I had no anomalous results; this proves that my results must have been fairly accurate. But I could make my results more accurate by keeping the solutions in a water bath to keep the temperatures accurate, because I know that temperature affects the rate of reaction. I could take 3 results so I could take a better average. We could use a colorimeter, which is an accurate piece of equipment, which measures light intensity. It could have picked up on the change of light intensity and then I could have recorded the time. So this would measure more accurately the point in which the marker was covered. We could use a burette to measure the volume of the solutions, as it is more accurate than measuring cylinders. Graduated pipettes would have made measuring more accurate because they measure to 0.0. Further Experiment We could investigate changing the temperature because the higher the temperature, the more kinetic energy so the particles move faster, more successful collisions therefore the rate of reaction is faster. If we did this we would have to keep the concentration of sodium thiosulphate and HCL constant. To get the substances cooler you could put them in an ice bucket. We must not heat acids higher than 60oC for safety and use a thermo stated water bath, as a Bunsen burner is not safe. We could investigate these temperatures 10, 20, 30, 40, 50, and 60. ?? ?? ?? ?? Ilana Greibach 10G Page 1 of 3 ...read more.

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