Question

A salt solution has a concentration of 2.4%w/v. What is the concentration if 10.0 mL of this solution is diluted to a total volume of 60.0 mL?

Answer 1

The concentration of the diluted solution is 0.4%.

Conc. of `NaCl` = 2.4 % w/v

Method 1:
10 ml of this solution diluted to a total volume of 60 ml, the dilution factor is 6 (10 ml/60 ml). Hence the concentration of the diluted solution is 2.4 % /6 = 0.4 % w/v

Method 2:
Concentration of initial solution is 2.4 %, which is same as 2.4 g `NaCl` in 100 ml.

Hence 10 ml of this solution will contain less `NaCl`
2.4 (g/100ml)*10ml = 0.24 g

Now 0.24 g of `NaCl` is present in a total volume of 60 ml, hence concentration (mass per volume) is
0.24 g/60 ml =0.004 g/ml, which in % becomes 0.4%.

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