Define two variables. Write a system of equations, and then solve. In a chemistry lab, you have two vinegars. One is 5% acetic acid and one
is 6.5% acetic acid. You want to make 60 L of a vinegar with 6% acetic
acid. How many liters of each do you need?

Step-by-step explanation:

Assume that the amount needed from the 5% acid is x and that the amount needed from the 6.5% acid is y.

We are given that:

The volume of the final solution is 200 ml

This means that:

x + y = 200

This can be rewritten as:

x = 200 - y > equation I

We are also given that:

The concentration of the final solution is 6%

This means that:

5%x + 6.5%y = 6% (x+y)

This can be rewritten as:

0.05 x + 0.065 y = 0.06 (x+y) > equation II

Substitute with equation I in equation II and solve for y as follows:

0.05 x + 0.065 y = 0.06 (x+y)

0.05 (200-y) + 0.065 y = 0.06 (200-y+y)

10 - 0.05 y + 0.065 y = 12

0.015y = 12-10 = 2

y = 2/0.015

y = 133.3334 ml

Substitute with the y in equation I to get the x as follows:

x = 200 - y

x = 200 - 133.3334

x = 66.6667 ml

Based on the above calculations:

The amount required from the 5% acid = x = 66.6667 ml

The amount required from the 6.5% acid = y = 133.3334 ml