Evaluation

The titration was done many times for each wine until a pattern of concordant results were obtained. An average was then calculated from those concordant results.

The sodium hydroxide and wine solution was left to stand for exactly 15 minutes each time, and accurate measuring equipment was used.

The equipment used was relatively accurate. Burettes and pipettes were used to measure out the wine and the iodine solution because they were the critical chemicals in the reaction, but the measurements may have been unreliable because different people measured out volumes and so there may have been different judgements. A measuring cylinder was used to measure out the sulphuric acid, which is not very accurate, but this does not affect the experiment because it is not a critical chemical in the redox reaction.

The experiment could have been improved, however, because it was difficult to judge the end point of each titration, so the volume of iodine used could be more or less than the stated amount used.
To minimise end point errors, a sample was kept at the side, and every titre was left to stand for a couple of minutes, before we compared them with the sample and judged as a group whether it had reached the same end point or not.

The experiment could be extended if we carried out titrations from a range of colombard-chardonnay wines from each country to see which country has, on average, more sulphite in their wine.