Question

Chemistry Molar Question..?

A certain metal hydroxide, M(OH)2 , contains 32.8% oxygen by mass. What is the identity of the metal (M) ?

I can't believe I'm getting tripped up by this one when more complicated ones seem easier.

Answer

As H has mass 1/16 of O the if the hydroxide is 32.8% O it is 32.8/16 = 2.05% Hydrogen.

Subtracting we get 65.15% M

Calculating the mole ratios gives

M = 1 O = 2 and H = 2

so the ratio of molecular masses is

65.15 /atomic mass of M : 32.8/32 : 2.05/2

So M x 32.8/32 =65.15 Atomic mass M = 63.6

M is Cu

Sep 11 at 14:47