This is MCQ # 826 of 1000 Pharmacy MCQs

Pharmaceutical Calculation Problem solution

826. 40 grams of a drug is added into 30 ml of a solvent. The density of the solvent is 1.5. What will be the concentration of the drug in the final product?
a- 26 %
b- 30 %
c- 40 %
d- 47 %
e- 60 %


Step-by-step solution:

To calculate the concentration of the drug in the final product, we first need to determine the mass of the solvent. We can use the formula:

mass = volume × density

Given the density of the solvent is 1.5 g/mL, we can calculate the mass of the solvent as follows:

mass = 30 mL × 1.5 g/mL = 45 g

Now, we have;

mass of the drug = 40 g
mass of the solvent = 45 g

To find the concentration of the drug, we need to find the mass fraction, which is the ratio of the mass of the drug to the total mass of the mixture. The formula for mass fraction is:

mass fraction = mass of drug / (mass of drug + mass of solvent)

Using our values:

mass fraction = 40 g / (40 g + 45 g) = 40 g / 85 g

So the mass fraction of the drug is:

mass fraction = 40 g / 85 g ≈ 0.4706

To express the concentration as a percentage, simply multiply the mass fraction by 100:

concentration (%) = mass fraction × 100 ≈ 0.4706 × 100 ≈ 47.06%

So the concentration of the drug in the final product is approximately 47.06%.

Thus the correct answer is d.