[beleting]

If 0.1000 g of a nickel hydroxide is added to water, and titrated against 0.1000 M HCl, the equivalence point is reached at 21.57 mL.  What is the charge on nickel in this compound?

[chenbeier]

Calculate the moles of HCl. This is equal to the half or third of Nickel hydroxide depending to the charge of the Ni. Convert to the mass by using the molar mass. Compare with given mass.

[beleting]

How would it be half or third? Are you going off of the two hypothetical balanced equations? Wouldn't that then be either a 1:1 or 1:2 ratio between nickel hydroxide and hydrochloric acid?

[chenbeier]

No, which Nickelhydroxides are existing. What does 1:1 mean , also 1:2 or 1:3.

[beleting]

Well for Ni⁺¹ . . .

NiOH + HCl    NiCl + H₂O

And Ni⁺² . . .

Ni(OH)₂ + 2HCl  NiCl₂ + 2H₂O

Ni⁺³

Ni(OH)₃ + 3HCl  NiCl₃ + 3H₂O

Or am I just wrong?

[beleting]

So I would find the mole for each hypothetical nickel hydroxide and compare that with the mole of HCl to find the one that simplifies to whole numbers?

[chenbeier]

Correct.

[beleting]

Thank you !