Question

If 75 mL of stock solution was used to make 375 mL of a 10% methanol solution, what was the concentration of the stock solution? Express your answer using 2 significant digits.

Answer 1

C1V1 =C2V2.

C1= concentration of the stock solution

V1= volume of stock solution to make a working solution,

C2- concentration of the working solution

V2= total volume.

C1= Needed to find out.

V1 = 75ml

C2 = 10%

V2 = 375 ml.

C1 *75 = 10% * 375

C1 = 10%*375 / 75

C1 = 50%.

So the concentration of stock methanol solution was 50%

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