Chem 253—TA: Josh Lovell
Lab 1: Effect of pH on a Food Preservative
Purpose: (1 point)
To determine whether a chemical change occurs when Sodium Benzoate is acidified to Benzoic Acid.
Theory: (2 points)
Sodium Benzoate is a common food preservative found in jellies, jams, sodas, fruit juices, etc... Its acid, Benzoic Acid, is an organic preservative that stops the growth of bacteria, yeasts, and molds.
Reaction: (3 points)
Reaction: sodium benzoate + hydrochloric acid ( benzoic acid + sodium chloride Amounts: 2.00 g Sodium benzoate, 5.0 mL 3M hydrochloric acid
+ HCl → + NaCl
Sodium benzoate is the limiting reagent due to the lesser number of moles.
The theoretical yield of Benzoic Acid is 1.695 g.
The actual yield of Benzoic Acid is:
Actual amount: 2.09 g Sodium benzoate, 5.2 mL hydrochloric acid Calculations:
The percent yield of this experiment is: [pic]
Methods/Procedures (1 point)
This experiment follows the instructions as found on page 44 of the Operational Organic Chemistry textbook with no exceptions. In all chemistry labs, protective eye-ware should be worn at all times in addition to long pants and closed-toed shoes. When handling HCl, sodium benzoate, and benzoic acid, gloves should be worn due to the corrosive nature of the compounds. If contact is made with skin, immediately flush with water and seek medical attention if severe. If inhaled, move to fresh air, or give artificial oxygen.
Observations/Results (1 point)
When the HCl was added to the mixture of water and sodium benzoate, a white creamy semi-solid substance immediately formed. The substance was relatively odorless. When dried with the vacuum, the substance had a powdery appearance...
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