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 31.5 mL of a 20.5 % solution to prepare a 11.04 % solution?

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lb equals 27 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 = `31.5\quadmL`.
    `C_1` = initial concentration = `20.5\quad%`
    `Q_2` = final quantity = `?\quad mL`.
    `C_2` = final concentration = `11.04\quad %`

    Therefore, rearranging the formula, we get:
    `Q_2 = (Q_1 × C_1)/(C_2)` `therefore Q_2 = (31.5 × 20.5) /11.04=58.5\quad mL` in nearest whole number.

    Now, subtract the initial quantity of the solution (`31.5\quadmL`) from this final quantity (`58.5\quadmL`) to determine the amount of solvent to be added: `58.5\quadmL-31.5\quadmL=27\quadmL`. (Ans)

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