SOLUTION: I need to make a diluted bleach solution of .005%. Using 250ml of water, how much bleach would I use to bring it to .005% dilution?

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Question 812981: I need to make a diluted bleach solution of .005%. Using 250ml of water, how much bleach would I use to bring it to .005% dilution?
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
The percent bleach in the final solution would be:
p+=+%28b%2F%28250%2Bb%29%29+%2A+100
where 'p' is the percent, b is the amount of bleach and (250+b) would be the total amount of the diluted solution.

We can substitute in the given percentage and solve for b:
0.005+=+b%2F%28250%2Bb%29+%2A+100
Simplifying:
0.005+=+100b%2F%28250%2Bb%29
Multiplying by 205+b (to eliminate the fraction:
%280.005%29%28250%2Bb%29+=+%28100b%2F%28250%2Bb%29%29%28250%2Bb%29
Simplifying:
%280.005%29%28250%2Bb%29+=+%28100b%2F%28250%2Bb%29%29%28250%2Bb%29
1.25+%2B+0.005b+=+100b
Subtracting 0.005b:
1.25++=+99.995b
Dividing by 99.995:
1.25%2F99.995++=+99.995b%2F99.995
Simplifying:
0.012500625+=+b (The decimal is a rounded-off approximation.)
So to get the desired dilution, add approximately 0.012500625 ml of bleach.