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Investigation to Determine the Composition of Commercial Vinegar.

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Introduction

Investigation to Determine the Composition of Commercial Vinegar Aim: To Determine the acidic concentration of different vinegars (as mol/dm3, g/dm3 and %). Introduction: Vinegar was discovered accidentally, over 10,000 years ago. It was discovered by a French man who left a cask of wine to go past its time. It turned into a wonderful new product. Through the centuries vinegar has been produced from many other materials including molasses, fruits, berries, melons, coconut, honey, beer, maple syrup, potatoes, beets, malt, and grains. But the principle remains the same - fermentation of natural sugars to alcohol and then secondary fermentation to vinegar. As recently as World War I, vinegar was being used to treat wounds. And today it is recommended for treatment of rashes, bites and other minor ailments when camping. There are different types of vinegar, these are just 3 of them: * Malt vinegar, made by the two-fold fermentation of barley malt or other cereals where starch has been converted to maltose. * Sugar vinegar, made by the two-fold fermentation of solutions of sugar syrup or molasses. * Spirit or distilled vinegar, made by the acetic fermentation of dilute distilled alcohol. For this experiment I will be using titration. This procedure can help you find the chemically equivalent volume of two solutions. ...read more.

Middle

7) When the colour change has been observed and recorded, dismantle and wash out the apparatus carefully. Phenolphthalein Colour Chart acidic solution. neutral solution. basic solution. Preliminary Results: Indicator / Vinegar Brown Vinegar Colourless Vinegar Screened Methyl Orange Dull Green Dull Green Phenolphthalein Bright Pink / Purple Bright Pink / Purple Conclusion: As I predicted, it was much easier to determine the end point with the Phenolphthalein Indicator than with the Methyl Orange. It was a much sharper change with the Phenolphthalein indicator and it took longer to determine the end point with Screened Methyl Orange Indicator. This means that in the titration experiment it will be much clearer when I have reached the end point using Phenolphthalein, giving me more accurate results. It also changed at pH 8.4 which means this is definitely the right indicator to choose. Prediction: I already know there is roughly 5% acetic acid in commercial vinegar so hopefully after the experiment has been completed and all calculations carried out, I should have roughly 5% concentrate of acid. If I get nothing like 5% I know I have anomalous results and either the experiment will have been carried out incorrectly or the solutions are contaminated. ...read more.

Conclusion

If I were to repeat this experiment I would take more readings to get a wider range of results to take an average over. This would give me much more reliable results. The one thing that was the hardest to measure was the end point. It is very difficult to accurately determine the exact end point. One way of combating this could have been by using a pH probe to see when the pH changes. The amount of vinegar in commercial vinegar varies form brand to brand, so it is not possible to say, on my findings, that every brown vinegar contains 5.04 % acetic acid and all clear vinegar contains 4.56 % acetic acid. Conclusion: As I predicted, in both cases, clear and brown vinegar, I achieved a result that was fairly close to 5% concentration of acetic acid. The results that I achieved were very small amounts which is one of the reasons why titration had to be used. It was also very important to be very accurate because the slightest degree in accuracy could have created anomalous results. This experiment seems to have been fairly successful, with consistent results achieved, and finding around 5% acetic acid in the vinegar as predicted earlier. I don't appear to have got any anomalous results which means they are good enough to make a reasonable conclusion on. 1 Stephen Bishop U5A ...read more.

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