### Dilution Problem - Find quantity of solvent

9. Altering Product Strength 9.1) Dilution 9.1.1) Dilution

9.1.1.1) Find initial concentration in dilution Easy 1

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Calculate the quantity of solvent you need to add into 32.5 mL of a 35.5 % solution to prepare a 5.78 % solution?

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lb equals 167 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 = 32.5\quadmL.
C_1 = initial concentration = 35.5\quad%
Q_2 = final quantity = ?\quad mL.
C_2 = final concentration = 5.78\quad %

Therefore, rearranging the formula, we get:
Q_2 = (Q_1 × C_1)/(C_2) therefore Q_2 = (32.5 × 35.5) /5.78=199.5\quad mL in nearest whole number.

Now, subtract the initial quantity of the solution (32.5\quadmL) from this final quantity (199.5\quadmL) to determine the amount of solvent to be added: 199.5\quadmL-32.5\quadmL=167\quadmL. (Ans)