Answer to Question #164179 in Biology for Amos

Question

20 tablets weighing 2g was powdered. Exactly 50mg was transferred to

100mL volumetric flask and diluted with water. 10mL aliquot was

transferred to another 100mL and diluted to volume. The A value of the

solution was 0.652 and the absorptivity value was 15mg/mL/cm. What is

the mg of paracetamol per tablet from the following data? Please

provide a step by step solution.

Answer 1

According to the absorption formula:

A = a b c,

where A - absorbance (0.652), a - absorptivity (15 mg/mL/cm), b - length of path (1 cm), c - concentration.

From here:

c = A / (a b) = 0.652 / (15 mg/mL/cm × 1 cm) = 0.0435 mg/mL

As a result, the second 100 ml flask contained 0.0435 mg/mL × 100 mL = 4.35 mg of paracetamol. From here, the first 100 mL flask contained 4.35 mg × 10 = 43.5 mg of paracetamol. It means that 50 mg of tablet contains 43.5 mg of paracetamol.

Since 20 tablets weigh 2 g, one tablet weighs 2 g / 20 = 0.1 g = 100 mg.

Finally, as 50 mg of tablet contains 43.5 mg of paracetamol, one tablet (100 mg) contains 43.5 mg × 2 = 87 mg of paracetamol.

Answer: 87 mg