A certain mass of an unknown third period metal hydroxide reacts with an certain volume and concentration of a diprotic acid. How do I figure out the identity of the metal?

Question

I used dimensional analysis and the molarity of the acid to find the moles of the acid, then multiplied it by the 1:2 stoichiometric ratio since it's a diprotic acid. This gave me the moles of the base. Then I divided the mass of the unknown base by the moles of the unknown base to get the g/mol. I subtracted the molar mass of the hydroxide to get the molar mass of the metal by itself, but my answer doesn't match any third period metals. I also tried ignoring the stoichiometric ratio, but it still doesn't work. What am I missing?

Answer 1

A third period metal hydroxide could be XOH, X(OH)₂ or X(OH)₃ so you don’t really know the mol ratio is 1:2. Is there additional information supplied in the problem. Was it a third period metal hydroxide or a third group metal hydroxide.?