Sample Calculations for Panacetin

Students are asked to do several calculations related to the Panacetin painkiller experiment. The following example calculations should be helpful. (Your weights may not match the weights in the example.)

Assuming a student isolated 0.5 g sucrose, 0.5 g aspirin, and 1.0 g of crude unkn, here’s what the calculations would look like:

% recovery

0.5 g +0.5 g + 1.0 g = 2.0 g recovered

if started with 3.0 g, then

(2.0 g/3.0 g)(100%) = 67% recovery

% composition

% sucrose = (0.5 g/ 2.0 g)(100%) = 25%

% aspirin = (0.5 g/2.0 g)(100%) = 25%

% unkn = (1.0 g/2.0 g)(100%) = 50%

total composition = 100% (composition total must be 100%)

Students are asked to compare their % composition to the label.

Label:

10% sucrose (8-12% is match)

40% aspirin (35-45% is match)

50% acetaminophen (45-55% is match)

Students are also asked to conclude if the painkiller contains acetaminophen, which is legal to sell in the U.S., or if it contains phenacetin or acetanilide, which are banned in the U.S.

For the phthalic acid crystallization, students should calculate the % recovery. So, if you begin with 1.00 g of phthalic acid and recover 0.71 g, you have a 71% recovery.