Dilution Problem - Find quantity of solvent

9. Altering Product Strength 9.1) Dilution 9.1.1) Dilution Find initial concentration in dilution Easy 1

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Calculate the quantity of solvent you need to add into 36 mL of a 39 % solution to prepare a 12 % solution?

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lb equals 81 mL kg

    This is a volume expansion or concentration dilution type problem. The essential formula is `Q_1C_1 = Q_2C_2`.

    `Q_1` = initial quantity = `36\quadmL`.
    `C_1` = initial concentration = `39\quad%`
    `Q_2` = final quantity = `?\quad mL`.
    `C_2` = final concentration = `12\quad %`

    Therefore, rearranging the formula, we get:
    `Q_2 = (Q_1 × C_1)/(C_2)` `therefore Q_2 = (36 × 39) /12=117\quad mL` in nearest whole number.

    Now, subtract the initial quantity of the solution (`36\quadmL`) from this final quantity (`117\quadmL`) to determine the amount of solvent to be added: `117\quadmL-36\quadmL=81\quadmL`. (Ans)