Question

How much water should be mixed with 25 ml of alcohol so as to obtain 25% alcohol solution?

Answer 1

Answer:

Assuming that the percentage alcohol in the original solution is % by volume, 12ml of 12% alcohol solution contains 12 * 12 /100 = 1.44ml of pure alchohol.

If we let X = the final volume of the 6% v/v alcohol solution we wish to make then we can write the following equation

6 = 1.44/x * 100

Multiplying both sides of the equation by x we get;-

6x=100*1.44

x=144/6 

x=24

Therefore if the final volume of the 6% solution is 24ml, we need to add;-

 (24-12) = 12 ml of water.