Investigating temperature change when different Volumes of acid and alkali are mixed.

Method

First of all we decided to use a plastic cup because it was easy to wash off the mixture. We poured out 30ml of Hydrochloric acid in to one measuring cylinder and poured 30ml of Sodium Hydroxide into the other measuring cylinder. Then we added the Sodium Hydroxide to the plastic cup and left it for 25-30 seconds, we then took the temperature of the alkali before adding the acid. We then tipped the Hydrochloric acid into the cup with the alkali. We stirred the cup for 25-30 seconds and then recorded the new temperature, and then we washed out the mixture before doing the next experiment. We then tried out different combinations- 40:20, 20:40, 15:45 and 45:15. Just to make sure we had reliable results we carried out the experiment twice and took an average from the two results.

                                                 

Results Table

1st Results

2nd Results

Average Results

Conclusion

From my results I can conclude that the Hydrochloric acid was two times as concentrated as the Sodium Hydroxide. The biggest temperature rise was when there were 20ml³ of Hydrochloric Acid and 40ml³ of Sodium Hydroxide because this creates the optimum mixture. From my graph I can recognise that the Hydrochloric Acid was 2molar and the Sodium Hydroxide was 1molar. Therefore the amount of H+ ions and OH- ions would be equal, when there are equal amounts of the two different ions they collide and neutralise with each other more, causing more heat to be released and a bigger temperature rise to occur. This type of experiment is also called an exothermic reaction.

Evaluation

Overall I thought are experiment went according to plan and we had accurate results. My results I received were good but I could improve the experiment by, carrying out the experiment more times this would improve the consistency of the results. Secondly I would put a lid over the plastic cup to help hold in the heat longer this would make the experiment more accurate. The final thing I would do is to conduct a bigger variety of different mixtures to make the experiment more precise e.g. 10:50, 35:25 and 25:35.

On my graph there were a couple of anomalous results I think this is due to human error and some of the heat may have been lost during the experiment.