Question

How much pure acid should be mixed with 5 gallons of a 50% acid solution in order to get an 80% acid solution

Answer 1

Let x repesent the amount of acid added

.50*5gal +1.00x = .80(5+x)

Simplify and Solve

.50*5gal +1.00x = .80*5+ .8x

.2x = .80*5 - .50*5

.2x =.3*5

.2x = 1.5

x = 7.5gal

checking our answer

2.5gal + 7.5gal = .8* 12.5gal = 10gal