Original Mixture: 10 liters, 25% acid = 0.25
Added mixture : x liters, 0% acid = 0 since it is pure water.
Total mixture: Volume = (10 + x), % = 10% = 0.1
Using mixtures formula:
Volume₁ * %₁ + Volume₂*%₂ = Total Volume*Total%
10*0.25 + x*0 = (10 + x)*0.10
2.5 + 0 = 10*0.10 + 0.1*x
2.5 = 1 + 0.1x
1 + 0.1x = 0.250
0.1x = 2.5 - 1
0.10 = 1.5
x = 1.5/0.1
x = 15
Amount of pure water to be added is 15 liters.
Hope this helps.
