Question

Calculate how many milligrams of the drug are contained in 2.0mL of a 3.0% (w/v) solution ofC₁₇H₁₉N₃O₃S

Answer 1

Ans. 3.0 % (w/v) means 3.0 gram of the drug in 100 mL of the solution.

Now,

100.0 mL of the solution has 3.0 gram of drug

        Or, 1.0 mL              -           -     (3.0 g / 100.0 mL) of drug

        Or, 2.0 mL             -           -     (3.0 g / 100.0 mL) x 2.0 mL of drug   

                                                = 0.06 gram of drug

                                                = 6 mg                         [1 g = 100 mg]

Thus, 2.0 mL of the given solution has 6.0 mg drug.