Results
Analysis
From this experiment, we have found out that if we halve the volume of gas, we double the pressure or vice versa – when we double the volume, we half the pressure. For example, when we increased the volume from 28.1 to 55.9, nearly doubling it, the pressure decreased from 196,000 to 101, 000, nearly halving. This is because as the gas is squashed into a smaller volume, it’s pressure increases due to the molecules of the gas being pushed closer together.
As you will see from the graph (over), there is an obvious trend in the results, and we can see that as the volume is increased, the pressure decreased. I have marked an example on the graph, the 20cm3 and 40cm3 volumes. The volume is doubles, and, as we can see, the pressure decreases from 275Pa to 140Pa – very nearly halved.
To conclude, I would say that the pressure is definitely related to the volume, which I already knew, and the results acquired and the graphs I drew from these results backed up this information. This is roughly what we said in our prediction, “I would say that when the volume is halved, the pressure will double.”
Evaluation
I think that the procedure we used was suitable for the equipment we had available to us and the time we had. The accuracy of our results was not optimal, but I think they are satisfactory. As always, a computer could have been used to improve our accuracy, for example if we had the appropriate programs, we could have connected the pressure gauge and volume scale to a computer, and so removed any possible human error and thus achieving accurate results. Despite all the areas of possible error, I did not recognize any anomalies from my graphs, so we now know that when the tubing came apart during the 297,000 Pa repeat, the following results were not greatly affected. There were also other possibilities where we could change the experiment to make it better and more accurate. For example, the tube that contained the gas was not the optimum shape, as the end was rounded, so the volume of gas was inaccurate. We could have easily increased the accuracy by repeating the results, but this would be very time-consuming, so we had to settle with approximate repeats, with similar volumes but not the same.
Overall, I think we got reliable results and they are good enough to support a firm conclusion. They were reliable because of the lack of anomalies and also the similarity between the results and our prediction. As further work, I could do another experiment using other gases, to see if that changes the relationship, although I do not think it will.
