SOLUTION: a chemist has 600 ml of a solution that is half acid. she needs 70% oof acid. how much acid should she add?

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Question 315380: a chemist has 600 ml of a solution that is half acid. she needs 70% oof acid. how much acid should she add?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = ml of acid to be added
In words:
(final ml of acid)/(total ml of solution) = 70%
%28300+%2B+x%29%2F%28600+%2B+x%29+=+.7
300+%2B+x+=+.7%2A%28600+%2B+x%29
300+%2B+x+=+420+%2B+.7x
x+-+.7x+=+420+-+300
.3x+=+120
x+=+400
She must add 400 ml of acid