SOLUTION: Annabell has 25 ounces of a 20% boric acid solution which she wishes to dilute to a 10% solution. How much water does she have to add in order to obtain the 10% solution?
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Question 1156013: Annabell has 25 ounces of a 20% boric acid solution which she wishes to dilute to a 10% solution. How much water does she have to add in order to obtain the 10% solution? Answer by ikleyn(52777) (Show Source):
Let W be the volume of water to dilute.
The amount of a pure acid is 0.2*25 ounces,
The total volume after dilution is (25 + W) ounces.
The equation for concentration is
= 0.1.
To solve, cross multiply
0.2*25 = 0.1*(25 + W).
Simplify
5 = 2.5 + 0.1W
W = = = 25.
ANSWER. 25 ounces of water.
Solved.
From the other side, the answer is OBVIOUS:
to dilute from 20% to 10%, Annabell must double the volume of the solution, i.e. add 25 ounces of water.
