The volume of the 39% acid solution that Roger needs to use to make a mixture of 86 mL of a 36% acid solution is 74.27 mL.
The mixture of the acids solutions is given by:
(1)
Where:
C: is the concentration if the mixture = 36%
V: is the total volume of the mixture = 86 mL
C₁: is the concentration of acid 1 = 39%
V₁: is the volume if acid 1 =?
C₂: is the concentration of acid 2 = 17%
V₂: is the volume of acid 2
The sum of V₁ and V₂ must be equal to V, so:
(2)
By entering equation (2) into (1), we have:
Changing the percent values to decimal ones:
Now, by solving the above equation for V₁:
Therefore, the volume of the 39% acid solution is 74.27 mL.
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