A solution of 45% acetic acid

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Question from Autumn, a student:

if a chemist has a 4 liter solution that consists of 90% acetic acid, how much water does he need to produce a solution of 45% acetic acid?
please explain the equation or formula used if possible. thank you.
a.j.

Hi,

If the 4 liter solution is 90% acetic acid then the amount of acetic acid in the solution is

0.90 × 4 = 3.6 liters.

After adding some water you have say x liters of a 45% solution. The amount of acetic acid is the same, 3.6 liters so

0.45 × x = 3.6 liters.

Solve for x.

Penny

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