(2) Quantity from volume and percent

3. Percent, Ratio, mg/mL, PPM, PPB 3.1) Percent 3.1.1) Percent - General

3.1.1.1) Percent from weight and volume Easy 1


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Calculate the mg quantity of solute required to prepare 195 mL of a lotion (concentration 0.82 percent weight by volume).


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lb equals 1599 mg kg

    Percentage (w/v) means number of grams of drug present per 100 mL of the solution. Here, the strength is 0.82 %, which means, there is 0.82 g of drug dissolved per 100 mL of a lotion. We need to determine the weight (in mg) of drug present in 195 mL of it.

    `∴ (0.82 \quad g)/(100 \quad mL) = x/(195 \quad mL) ⇒ x = 1.599 \quad g`

    1 g equals 1000 mg.

    ∴ there will be `1.599 g × (1000 mg)/(1 g) = 1599` mg drug present. (Ans).