Astudent 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+]?

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

Mgo2 is the oxidation state of manganese oxide