Question 164105: A chemist has 60 g of a solution that is 70% acid. How much water should be added to make a solution that is 40% acid? Answer by ptaylor(2198) (Show Source):
You can put this solution on YOUR website! Let x=amount of water needed
Now we know that the amount of pure acid in the 60g solution (0.70*60) plus the amount of pure acid in the water that's added(0) has to equal the amoount of pure acid in the final solution (0.40(60+x)). So our equation to solve is:
0.70*60=0.40(60+x) get rid of parens (distributive law) and simplify
42=24+0.40x subtract 24 from each side
42-24=24-24+0.40x collect like terms
18=0.40x divide each side by 0.40
x=45g-------------------------------------amount of water needed
CK
0.70*60=0.40*105
42=42
Hope this helps---ptaylor
