I have drawn two lines of best fit on my graph, because the first line I drew didn’t go through all the points but it did go through (0,0) whereas the second line went straight through three points, which were points two, three and four. The reason that the first line of best fit did not go through any points is that I would have expected points one, two, four and five to have been lower on my graph.
The Prediction
I predicted that if I double the concentration of Sodium Chloride ions in a solution the current that can flow through the circuit would also double. The prediction was not correct because the current did not double, although I think that if the concentrations were lower, for example 0.1M – 1M the prediction would have been correct. I think this because as the concentration gets higher more Sodium reacts with the water in the beaker, and more Chlorine gas, together these reactions form bubbles and these bubbles form on the electrodes, which makes it harder for the ions to get to the electrodes. Therefore if the concentrations were lower there would be less reactions occurring resulting in the electrons being able to flow through the circuit easily.
Evaluation
Anomalies in the evidence
Scientific Explanation of the Anomalies
The reason there were anomalies in the evidence could have simply been due to there being too many extra gases. It could have been that the electrodes were too close together or the temperature was too hot.
Improvements to the procedure
- Always use the same equipment because as we noticed using different equipment gives very varied results, which are unexpected.
- Use plastic to hold the electrodes instead of just cork.
- Could produce more results, as we did not have enough results to show us if the theory is correct or not.
Further work
I actually carried out further work into the concentration of the solution. I did the experiment again in the same way but I tried it using 0M-1M.
The results turned out how I had expected them to, which means I was right to think that if the concentrations were lower the prediction would be correct. This is because as the concentration gets higher more Sodium reacts with the water in the beaker, and more Chlorine gas, together these reactions form bubbles and these bubbles form on the electrodes, which makes it harder for the ions to get to the electrodes. Therefore as the concentrations were lower there must not have been as many reactions occurring, leaving it easier for the ions to get to the electrodes.
