I am going to investigate the effect of temperature on the rate of a chemical reaction, between Sodium Thiosulphate and Hydrochloric Acid. I am going to follow the course of the reaction by drawing a cross on a sheet of paper and placing the beaker containing the reaction over it, I will wait and time with a stop watch until the (sulphur) solid is thick enough to obliterate the cross on the paper in a ‘cloudy’ liquid.
I predict that the reaction time will change when the temperature is altered. I think that the higher the temperature the less time the course of reaction will take. This is because the particles move faster, which causes the likelihood of successful collisions (reaction) to happen, and if the temperature were to be decreased, the reverse would happen.
I am going to measure/observe the reaction by starting the stopwatch when the chemicals are mixed and stopping it when the suspension of sulphur in the liquid becomes thick enough to cover the cross, and recording the time the reaction takes. On each experiment, the temperature will be raised by putting a higher temperature of water into a large beaker and placing the beaker containing the reacting in the water when the sufficient temperature is reached. I am going to keep the concentration, volume, use the same cross each time and have the same person say when the cross has been obliterated, this is to ensure that the experiment is a fair and unbiased as possible. Keeping the concentration and volume is important because if different concentrations are used the higher or lower the concentration will cause the experiment to be fair, the same rule for volume. I must use the same cross and person each time because everyone has a different degree of eyesight and if the cross is a different colour/size that person may find different colours and sizes easier to see than others.
To measure the time I will use a stopwatch, record the temperature I will use a thermometer. To contain the chemicals I will use beakers, the measurements of the chemicals are 5ml Hydrochloric acid, 50ml Sodium Thiosulphate and 15g/1 of Sodium. For safety reasons I will keep my goggles on at all times.
Katie Sutton
Chemistry Coursework
Investigating Rates of Reaction
Results
Method
I put 50ml of Sodium Thiosulphate with a concentration of 15 g/1 in a beaker. I them put the beaker onto a piece ofpaper marked with a large cross and recorded the temperature.I added 5ml of Hydrochloric acid to the Sodium Thiosulphate and timed the reaction time, once the cross had been obliterated I stopped the stopwatch.
I did this experiment 8 times keeping everything the same except for the temperature with was risen each time by 4 C. this was accomplished by putting the beaker containing the chemicals into a larger beaker of water. The desired temperature, which was achieved by leaving kettle water to cool until the certain temperature was achieved.
Katie Sutton
Chemistry Coursework
Investigating Rates of Reaction
Conclusion
My prediction was correct, the higher the temperature, the faster the reaction.
This was because when the Sodium Thiosulphate is heated, the particles move around faster, increasing the likelihood of successful collisions. When the Thiosulphate particles collide with the Hydrochloric Acid, energy is passed on causing them to react. The higher the temperature of the particles the more energy in them. This explains the results on my graph, which apart from a few
