Molecular Weight Determination of Ethyl Benzene Product

1.             Write a balanced equation for the titration

2.             Accurately (to three decimal places) weigh 0.2 gm. of your dried product into a 250-mL Erlenmeyer flask and dissolve it in 25-mL 95% Ethanol.  Titrate the solution with 0.100 M NaOH to a faint pink end point, using 3 drops of phenolphthalein as your indicator. Calculate your equivalent weight using the following equation.

3.             Calculate your molecular weight and compare it with that at the beginning of the experiment.

4.             Calculate the % difference.

                                                   grams of acid

Molecular weight =    -------------------------------------------------------------------

                                 ( volume of base consumed in liters ) x M

5.             Record this calculation in the Results section of your lab report.

6.             Any remaining benzoic acid should be returned to the recovery jar in Hood #1.