how many milliliters of water should be added to 1.5 liter of a 20% w/v solution to prepare one containing 12% w/v solute?
Let x be the mL of water we are looking for.....and pure water = 100% water = 1.00
20% solution = 80% water= .,80
12% solution = 88% water = .88
And 1.5 L = 1500mL
So we have
x (1.00) + 1500 (.80) = .88 ( 1500 + x) simplify
1x + 1200 = 1320 + .88x
1x - .88x = 1320 - 1200
.12x = 120 divide both sides by .12
x = 1000mL of water