Chem 253- TA: Gia Hoang
Lab 1: Effect of pH on a Food Preservative
The purpose of this lab was to determine if a new substance forms when sodium benzoate is placed in a simulated stomach acid.
Benzoic acid can be found in a wide variety of plants. It is used as a natural preservative in many foods. Sodium benzoate, the salt of benzoic acid, has become a more popular choice as a food preservative because it is more soluble in water than benzoic acid. Many food items found today are preserved with sodium benzoate.
Reaction: sodium benzoate + hydrochloric acid benzoic acid + sodium chloride Amounts: 2.00 g 5.0 mL 3M
+ HCl → + NaCl
Because there are less moles of sodium benzoate, it is the limiting reagent.
The theoretical yield of Benzoic Acid is 1.706 g.
The actual yield of Benzoic Acid is .754 g.
The percent yield of this experiment is:
The experiment was done according to the textbook as found on pages 40-47 using the Standard Scale directions. Safety issues that were accounted for were that both sodium benzoate and benzoic acid are irritants. Safety goggles were worn and care was taken to ensure that none spilled onto skin or clothes. Hydrochloric acid is a strong acid and is very corrosive. Care was taken not to get any on clothes, skin, or into eyes.
After the sodium benzoate was mixed into the water and the HCl was added, the solution underwent a color change from a clear substance to a white substance. Also, a precipitate began to form. This precipitate was a dry, white solid with a mass of .754 g.
My results seem to be a little askew. While the...
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