The above diagram shows the experiment that I shall do to test the way that temperature affects the speed of the reaction, Magnesium + hydrochloric acid → magnesium chloride + hydrogen.
Explanation of the diagram
I will mix the 2 substances that I will use for the experiment, magnesium and hydrochloric acid in a test tube. I will then seal the test tube with a bung, and place a tube connecting it. The tube will enable any hydrogen created in the reaction between magnesium and hydrochloric acid to pass through the tube into the other test tube. The hydrogen passing to a separate inverted test tube that will be full of water and immersed in a ice cream tub full of water through the tube will create bubbles in the inverted test tube. When the hydrogen stops flowing (creating bubbles in the inverted test tube) we will know that the reaction has stopped, because hydrogen will only flow out of the tube when there is reactions between the magnesium and chloride particles.
Measuring and experiment details
To investigate temperature change I will need to the change the temperature of the mixture in the reaction. I will complete 6 different experiments each at a different temperature, starting at 10°C going upwards in 10 °C intervals up to 60°C; I will repeat each experiment.
I will get the correct temperatures for the mixture for each experiment by placing the beaker with the acid in, into an individually set water bath for each experiment. Once the acid is at the correct temperature I will add it to the appropriate place in the pre-set position in the experiment apparatus shown above.
Once the experiment is underway I will time how long it takes for the magnesium to disappear, once it has I will stop the clock. I will use 25ml of hydrochloric acid and 10g of magnesium for each experiment and I will keep the equipment and the room temperature constant during the experiments. This will make a fair test. To keep the experiment safe I will take extra precaution when handling acid and always wear goggles.
Results
The results show that my prediction was correct, as the temperature increases the speed of the reaction increases. I have found out that there is a positive correlation between the temperature increase and the speed of the reaction.
Evaluation
I could have improved the experiment by using more accurate equipment this would have made the experiments more accurate. I could have also done the experiment under more precise and constant conditions (e.g. if the room temperature for all the experiments was exactly 20.6°C). I could have also completed more repetitions of the experiments; this would have made the results more reliable. Also when heating the acid you are not heating the metal. So when the medal is added to the acid in the experiment set-up there could be a temperature change in the mixture causing inaccuracies.
I believe that all the results taken were good, none were anomalous. The only result that could be slightly anomalous is the 1st result taken at 10°C, but this is only slightly different to the second result, and when the average is taken the chart and line of best fit evens out well.
The evidence strongly confirms my prediction, it is clear that as the temperature increases the reaction time decreases. This proves my theory and I am happy with the way the experiment has been undertaken.