A Chemist has 100g of 25% acid solution. How much of these solution he needs to drain and replace with 70% acid solution to obtain 100g of 60% acid solution?
Accepted Solution
A:
to solve this kind of problem, there are two concepts: the total amount of solution and the total amount of acid
in this case, suppose there are x grams of the 25% solution, y grams of the 70% of soltuion x + y = 100 => y= 100-x 0.25x + 0.7y =0.6 *100 =60 replace y with 100-x: 0.25x + 0.7(100-x)=60 0.45x=10 x= 22.22 100-22.22=77.78 so he needs to drain about 77.78 grams of the solution.