Using Mass/Volume Percent to Find Mass of Solute

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Q1. A topical antibiotic is 1.0% (m/v) clindamycin. How many grams of clindamycin are in 60. mL of the 1.0% (m/v) solution?

Q2. In 2010, the FDA approved a 2.0% (m/v) morphine oral solution to treat severe or chronic pain. How many grams of morphine does a patient receive if 0.60 mL of 2.0% (m/v) morphine solution was ordered?

Solution

Step 1 State the given and needed quantities.

Step 2 Write a plan to calculate the mass.

Step 3 Write equalities and conversion factors. The percent (m/v) indicates the grams of a solute in every 100 mL of a solution. The 1.0% (m/v) can be written as two conversion factors.

Step 4 Set up the problem to calculate the mass. The volume of the solution is converted to mass of solute using
the conversion factor that cancels mL.