Molarity

[Jessica Esparza 2H]

What would be the proper steps to answer the following question? The molar mass of the metal hydroxide M(OH)2 is 74.10g per mole. what is the molar mass of the sulfide of this metal?

[claribel charway 1I]

First you need to subtract the mass of (OH)x2 from the molar mass of the metal. When subtracting you find out the unknown metal is calcium.
74.10 - 34.02 = 40.08
Next, add the mass of Sulfur to the remaining amount. This is adding the masses of Calcium and Sulfur to create calcium sulfide.
40.08 + 32.07 = 72.15

[Ryan Yee 1J]

So the metal hydroxide just basically means that the metal 'M' is combined with two hydroxide ions (OH^-)2. You want to find the sulfide of this ion, or what the molar mass would be when combined with an S^2-. Taking away the molar mass of hydroxide would mean subtracting 2(17.01) from the original molar mass to get 40.08, which is about the mass of calcium. Calcium combines with sulfur to form calcium sulfide (CaS) and would have a molar mass of 72.14.

[Jarrett Peyrefitte 2K]

The first step is to find out what the unknown metal is. To do this you must take the given molar mass and subtract it from the mass of the two hydrogens and oxygens.

74.10 - ( 2x1.008+2x15.999) =39.94 g/mol

Then you must find this molar mass on your periodic table, and this molar mass comes out to Calcium (Ca).

Then solve for calcium sulfide

40.078+32.05=72.13 g/mol

[Jessica Esparza 2H]

Thank you, everyone, for your help!