SOLUTION: How many ml of water should be added to 15 ml of a 20% acid solution to produce a 5% acid solution?

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Question 709269: How many ml of water should be added to 15 ml of a 20% acid solution to produce a 5% acid solution?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
The water to add is 0% acid. This means it is part of the volume change but not part of the quantity of acid change. ONE variable.

let v be the volume of water to add to the 20% acid. Result of the mixture must be 5% acid.

15%2A20%2F%28v%2B15%29=5
5%28v%2B15%29=15%2A20
5v+5*15=15*20
5v=15*20-5*15
5v=15(20-5)
5v=15*15
highlight%28v=45%29, ml. of water to add.