Problema Solution
In your chemistry class you have a bottle of 5% boric acid solution(x) and a bottle of 2% boric acid solution(y) . You need 60 milliliters of a 3% boric acid solution for the experiment that you are doing. How much of the 5% and the 2% must you mix together to get a 3% solution?
Answer provided by our tutors
let
x = ml of 5% boric acid solution needed for the mix
y = ml of 2% boric acid solution needed for the mix
the mix is 60 milliliters of a 3% boric acid solution thus
x + y = 60
the boric acid in x + the boric acid in y = 3% of 60
0.05x + 0.02y = 0.03*60
0.05x + 0.02y = 1.8 multiply both sides by 100
5x + 2y = 180
by solving the system of equations
x + y = 60
5x + 2y = 180
we find
x = 20 ml
y = 40 ml
click here to see the step by step solution of the system of equations
we must mix 20 ml of the 5% and 40 ml of the 2% boric acid solution to obtain 3% solution.