A student added 25.0 uL of a solution of magnesium chloride to a microcentrifuge tube along with a color changing indicator, and titrated with 1.00 x 10−2 M EDTA to the endpoint. The color change occurred at 21.7 uL. What was the [Mg2+]?

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Hagrid
To solve this, we equate the equivalence of Magnesium chloride and EDTA. Since MgCl2 is a salt, we can assume that it fully dissociates into ions in solution form. So,
equivalence of MgCl2 = equivalence of EDTA
25 uL (N) = 21.7 uL (1.00 x 10 -2)
N = 8.86 x 10 -3
M = N / 2
M = 4.34 x 10 -3

Therefore,
[Mg2+] = 4.34 x 10 -3