The Effect of Ph on a Food Preservative Essay
698 WordsOct 1st, 20123 Pages
The Effect of pH on a Food Preservative
September 18, 2012
To study the affect of pH on a food preservative.
Chemical Equation: C6H5COONa + HCL ------ C6H5COOH + NaCl
This experiment was started with a clear solution of sodium benzoate and HCl was added to it, ultimately producing benzoic acid. First, .3395 g of sodium benzoate was weighed, then it was dissolved in water, causing it to disassociate into ions. Next, 3M of HCl were added drop wise to the solution until it reached a pH of 2, thus introducing the hydronium ion. This addition caused a white, solid benzoic acid to precipitate out of the solution. A vacuum filtration system was used to separate the solid from the liquid. What was once…show more content…
Once, the precipitate was ready to be placed in the oven there was not enough time to allow for it to dry for 10 minutes. The precipitate was only in the oven for about 5 minutes, therefore, when weighed there was excess liquid in the precipitate. The final weight of the precipitate was .45 g which was more than the amount that was started with. From this end weight, it can be deduced that there was excess liquid in the end result.
Post-Lab: 1. The experiment began with a clear solution of sodium benzoate, once 3 M of HCl were added to achieve a pH of 2, the clear solution became a precipitate. Sodium benzoate was water soluble, but the yield of benzoic acid became quite insoluble in water.
3b. Although, a low amount of HCl was used, the waste can still cause health risks and risks to the environment because it was not just one person doing the experiment, therefore increasing the waste of HCl. Water was also used to wash the vial to remove all solids that might be sticking to the side of the vial, therefore, wasting water, which is not green.
4. If you start adding NaOH to the solution in small amounts, NaOH neutralizes part of the HCl, (moles of HCl to moles of NaOH) so the pH begins to increase slowly, this raises the soluability. This allows for the equivalent point to be reached: moles of HCl = moles of NaOH. By continuing to add the NaOH, pH will
Essay on Lab1: Effect of Ph on Food Preservatives
1343 WordsJun 17th, 20136 Pages
Lab 1: Effect of pH on sodium benzoate, a food preservative
Sheikh M Zakaria
Person no. 36295651
TA: Synthia Gratia
Date of Submission: 05/29/13
Abstract Sodium Benzoate is a common food preservative used in food products such as jams and jellies, soft drinks, pickles, condiments etc and in tinned products in the market. This experiment aimed to determine whether benzoic acid is formed from it’s superior soluble form sodium benzoate in stomach acid, which is simulated by HCl (pH=2). It has been seen that at a low optimum pH, i.e. in the presence of sufficient hydrochloric acid, sufficient benzoic acid is yielded. The percentage yield is determined from the calculations of the theoretical (stoichiometric) calculations and the actual…show more content…
The percentage yield calculation reveals that approximately 90% of benzoic acid as white precipitate were recovered from the reaction. There were a number of factors which might have contributed to the 10% deficiency in the final yield. It needs to be mentioned though that a percentage yield of less than 100% is achieved because the drying of the solid mass after vacuum filtration was sufficient to give a practical number. During measurements of mass of benzoate and benzoic acid when it’s formed, there were obvious human errors involved. Some benzoates were lost while transferring to the conical reaction vial from the watch glasses, and further loss of the product benzoic acid might have taken place when the solution mixture was tipped on the Hirsh funnel. We couldn’t determine if the reaction was complete or not, so we might not have had all the salt converted 4. The solution might not have sufficiently and gradually cooled though every effort was made for that, hence there could be lack of benzoic acid crystals forming.
The litmus test might have contributed to a significant loss of the precipitate, but only one instead of multiple tests were performed to see if the reaction mixture was acidic enough. Given the carefully controlled experiments and the 90% yield, it can be deemed that the methods used to perform the experiments are full proof and performed as immaculately as possible.
The fact that a