What volume of a 2.5 m stock solution of h3po4 is needed to prepare 3.8 l of a 1.5 m h3po4 solution? 1.0 l 2.3 l 5.7 l 6.3 l

To prepare a solution from different concentration stock, you need to make the content/mass of solute equal. The content is calculated by multiplying the concentration with the volume used.
The calculation would be:

content1= content2
V1 * M1= V2 * M2
V1 * 2.5M= 3.8L * 1.5 M
V1= 5.7/2.5= 2.28L = 2.3L

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