let

x = liters of the 10% acid solution

y = liters of the 5% acid solution

A scientist wishes to make 2 liters of an 8% acid solution by mixing a 10% acid solution and a 5% acid solution:

x + y = 2

0.10x + 0.05y = 0.08*2

by solving the above system of equations we find:

x = 1.2 L

y = 0.8 L

click here to see the step by step solution of the system of equations:

the chemist should use 1.2 liters of the 10% acid solution and 0.8 liters of the 5% acid solution.