Preliminary
When conducting this part of the experiment I started off by trying the experiment on the lowest reading on the power pack which was 0.2v. This was to low as it would take too long to get a good reading so I put it up to 4.0v which was adequate as it only took 30s to get a good reading, so I used 4.0v, 4.2v, 4.4v, 4.6v, 4.8v 5.0v.
Diagram
Method
Preliminary
When conducting this part of the experiment I started off by trying the experiment on the lowest reading on the power pack which was 0.2v. This was to low as it would take too long to get a good reading so I put it up to 4.0v which was adequate as it only took 30s to get a good reading, so I used 4.0v, 4.2v, 4.4v, 4.6v, 4.8v 5.0v.
Diagram
Method
- Set up equipment as above.
- Fill a measuring cylinder with water, and invert over the cathode.
- Set the power pack at the voltage required.
- Time for 30s and record results.
As electrons flow to the cathode, positive ions are attracted to it. When Cl- ions reach the cathode it loses its electrons. This will give off Cl2 gas. As the gas is given off it will begin to fill the inverted measuring cylinder displacing the water. We can then measure the amount of gas that has been given off in a certain length of time according to how much water has been displaced.
Results
Evaluation
I have managed to conclude from my results that the voltage affects the amount of gas given off, but my results and my graph do not entirely support this. On my scatter graph there is a slight correlation but it is not strong enough to allow me to make any definite assumptions. There are two many anomalous results. There are a number of possible reasons for this: the electrodes may not have been entirely clean and this could impinge on the amount of gas given off.
Really the experiment should be performed with a new electrode for every test to ensure that it is completely clean, but this would become costly.
There is a possibility that the concentration of NaCl varied between readings, because we used water in the measuring cylinder to measure the amount of gas given off. As this was inserted into the Brine solution, the water would mix with the brine and alter the concentration. To prevent this, I should have put brine in the measuring cylinder.
Another possible reason for the anomalous results could be that it is almost impossible to collect all the gas that is given off for every reading this may mean that I did not collect the entirely correct results for every voltage.
