### Dilution Problem - Find Initial Concentration

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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What concentration of a 28.5 mL solution do you need to make 240 mL of a 2.43% solution?

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lb equals 20.5 % 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 = 28.5\quadmL.
C_1 = initial concentration = ?\quad%
Q_2 = final quantity = 240\quad mL.
C_2 = final concentration = 2.43\quad %

Therefore, rearranging the formula, we get:
C_1 = (Q_2 × C_2)/(Q_1)

therefore C_1 = (240 × 2.43) /28.5=20.5\quad% (Ans.).

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