How much water should be added to 70ml of 60 percent acid solution to dilute it to a 50 percent acid solution?

14 ml of water

Explanation:

To find the volume you need to dilute the concentration of a solution, you should use the formula C1 x V1 = C2 x V2 in which:

C1 = initial concentration (in this case 60 %)

V1 = initial volume (in this case 70 ml)

C2 = Final concentration (you want to dilute until 50 %)

V2 = final volume (the variable you want to search)

So you need to:

1. - Isolate the variable you want to find: V2 = (C1 x V1) / C2

2. - Substitute dа ta: V2 = (60% x 70 ml) / 50 %

3. - You do the math, in this case is 84 ml.

4. - Remember that you have a initial volume of 70 ml, so the difference (84 ml - 70 ml = 14 ml) is the volume you need to add to dilute your solution.