### Dilution Problem - Mixed category

9. Altering Product Strength 9.1) Dilution 9.1.1) Dilution

9.1.1.1) Find initial concentration in dilution Challenging 1

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Calculate the quantity of solvent you need to add into 43 mL of a 37.75 % solution to prepare a 5.67 % solution?

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lb equals 243.5 mL kg

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

Q_1 = initial quantity = 43\quadmL.
C_1 = initial concentration = 37.75\quad%
Q_2 = final quantity = ?\quad mL.
C_2 = final concentration = 5.67\quad %

Therefore, rearranging the formula, we get:
Q_2 = (Q_1 × C_1)/(C_2) therefore Q_2 = (43 × 37.75) /5.67=286.5\quad mL in nearest whole number.

Now, subtract the initial quantity of the solution (43\quadmL) from this final quantity (286.5\quadmL) to determine the amount of solvent to be added: 286.5\quadmL-43\quadmL=243.5\quadmL. (Ans)