Hence this method is clearly seems to semi quantative and has sever limitations, too much is left down to estimation which is where human error could easily occur this is because in betweens cannot be accurately measured and have to be guessed at. In conclusion the method seems to flawed in the respect of accurately measuring the glucose concentration of solutions.
In order to make the experiment a ‘fair test’ there were three main variables which needed to be kept constant.
1) Firstly the volumes this included all measurements i.e. the amount of benedict’s solution used and the amount of glucose water solution in each test tube.
2) Secondly the time that all the test tubes were kept in the water bath had to be the same for all test tubes including solution X. This is because the colour may have developed more or less depending on the time left in the water bath.
3) Thirdly temperature in the water bath had to remain the same for all of the test tubes because this could also have affected the colours of the solutions hence affecting the results.
The time in the bath and the temperature in the bath were very simple to keep constant because all test tubes were put in the same bath at the same time and taken out at the same time. Therefore all test tubes were exposed the same water bath conditions.
During this experiment I learnt three new techniques:
1) SERIAL DILUTION: This involves the removal of a small amount of an original solution which is then added to another container which is the brought up the original volume using the required buffer or water. Then this process is repeated from the second and so on and so forth until sufficient dilutions have been made. In our experiment it involved starting with 10ml of 10% glucose solution then adding 1ml of this to 9ml of water giving 1% glucose solution this was done in succession for five test tubes.
Serial dilutions are a useful technique because they are an easy was for us to make solutions of varying concentrations in succession. This method is desirable because it eliminates a lot of the uncertainty and imprecision involved in making very small concentrations relative to the stock solution. For example it would have been very difficult to have measured out 0.0001% glucose using any other method.
2) THE TWO BEAKER WASH: The second method I learnt was the two beaker wash this is simply an efficient way of cleaning your syringe. It involves filling one beaker full of distilled water and leaving another empty then filling your syringe full of distilled water then emptying it into the beaker, this process should repeated 3 times for thorough cleaning. Although this is a simple technique it is very important to wash your syringe when changing between concentrations because your results can easily be influenced by residue of ‘left over’ from the previous concentration.
3) SELECTION OF SYRINGE: The third method I learnt was simply how to select the best syringe for the job. When selecting the size of your syringe you should always pick the smallest syringe that it is possible to do the job with on one pump of the syringe. This is to add accuracy.