A chemist is making 200 l of a solution that is 62% acid. he is mixing an 80% acid solution with a 30% acid solution. how much of the 80% acid solution will he use?

Answer: 72L of 30% and 128L of 80%

You can determine the weight of the acid by multiplying the concentration with the volume. Let say v1 is the volume of 30% solution needed and v2 is the volume of 80% solution.

The weight of acid from the used solution should be equal to the product. You can get this equation

final solution = solution1 + solution2

200l * 62% = v1 * 30% + v2*80%

124L = 0.3v1 + 0.8v2

124L - 0.3v1 = 0.8v2

v2=155L - 0.375v1

The total volume of both should be 200l. If you use the previous equation, you can calculate:

v1+v2=200L

v1 + (155L - 0.375v1) = 200L

0.625v1 = 200L - 155L

v1 = 45 / 0.625 = 72L

v1+v2=200L

v2 = 200L - 72L = 128L