Cliffs AP Chemistry, 3rd Edition

To determine the purity of the ASA that was produced, the student then measured out

0.400 g of the ASA that he produced and treated it with NaOH followed by the Fe−Cl 3 −

KCl−HCl solution and then diluted as before. The transmittance of the Fe3+complex pro-

duced from a 5 mL aliquot of ASA synthesized in this experiment was 14%. The reason

that the transmittance was taken was because transmittance is a linear scale and the read-

ings were more precisely obtained. Convert the %T to absorbance.

A = 2.000 −log (%T) = 2.000 −log(14) = 0.854

6. From the Beer’s law plot, determine the concentration of the ASA produced.
   From Figure 2, an absorbance of 0.854 corresponds to a 4.27× 10 –4M concentration of
   the salicylate complex.


7. Calculate the mass of ASA in the sample produced.

4

L

4.27 10 mol ASA

1 mol ASA

180.17 g ASA

1

# 100. mL standard sol’n

= ##

1000 mL

1L

5.00 mL

250. mL
     ##=0.385 g


251. Calculate the percent ASA in the sample produced.

.

.

g sample %.%

g ASA

0 400

0 385

# 100 =96 3

9. The melting point of the ASA produced was determined as 134 °C as compared to the
   known value of 135 °C. Comment on the disparity.
   The melting point of the ASA is very close to known literature values. The melting
   occurred over a very narrow range and was distinct. This confirms a fairly pure synthesis
   of 96.3%.

Laboratory Manual Resources

1. Vonderbrink, SallyAnn, Laboratory Experiments for Advanced Placement Chemistry,
   Flinn Scientific, Inc., Publishers, Batavia, IL, 1995.


2. Chemical Education Resources, Inc., Modular Laboratory Program in Chemistry,
   Palmyra, PA.

Part III: AP Chemistry Laboratory Experiments