Question

a tablet of benadryl (r), an antihistamine, has a mass of 0.48 g. it contains 24 mg of the active ingredient, diphenhydramine hcl.
part a
what percent of the tablet is active ingredient?
express your answer using two significant figures.

Explanation:

Step1: Convert units to be consistent

First, convert the mass of the active ingredient from milligrams to grams. Since \(1\space g = 1000\space mg\), then \(24\space mg=\frac{24}{1000}\space g = 0.024\space g\).

Step2: Calculate the percentage

The formula for percentage is \(\text{Percentage}=\frac{\text{Mass of active ingredient}}{\text{Mass of tablet}}\times100\%\). Substitute the values: \(\text{Percentage}=\frac{0.024\space g}{0.48\space g}\times100\%\).
Simplify the fraction \(\frac{0.024}{0.48}=\frac{24}{480}=\frac{1}{20}\). Then \(\frac{1}{20}\times100\% = 5.0\%\) (using two significant figures).

Answer:

\(5.0\)