Question 97708: A nurse has 1 liter of a solution that is 20% alcohol. How much pure alchol must she add to bring the solution up to a 25% concentration Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! A nurse has 1 liter of a solution that is 20% alcohol. How much pure alcohol must she add to bring the solution up to a 25% concentration
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20% solution DATA;
Amt. = 1 liter ; amt of active ingredient = 0.20x liter
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100% alcohol DATA;
Amt. = x liter; amt of active ingredient = x liter
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25% Mixture DATA;
Amt. = (1+x) liter ; amt of active ingredient = 0.25(1+x) = 0.25+0.25x liter
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EQUATION:
active + active = active
0.20x + x = 0.25+0.25x
1.2x = 0.25 + 0.25x
0.95x = 0.25
x = 0.263 liter (amount of pure alcohol that must be added)
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