Textbook Question E15

[Fiona Latifi 1A]

For question E15, would OH be the sulfide of the metal? Or would it be (OH)2? Thanks.

[Sahil Jog 1F]

I think what they're asking is that the metal in the compound is unknown, so they just labeled the unknown metal M. And so, since we know the molar mass of the Metal Hydroxide (M(OH)2), they want to figure out the molar mass when the metal is bonded to sulfur, as such a metal sulfide (MS).

[Sally Qiu 2E]

The (OH)2 is the hydroxide. The sulfide of the metal is going to have sulfur in the formula. I believe the problem wants you to find the mystery metal M, then find the formula of the sulfide of the metal.

[Andrew Liang 1I]

The problem has given us that a mystery metal hydroxide M(OH)2 is 74.10 g.mol-1
1. We need to find out what the metal is
-----> (74.10 g.mol-1) - (34.02 g.mol-1 of (OH)2) = 40.08 g.mol-1
2. Determine the metal
-----> From the periodic table we can see that Calcium has the molar mass of 40.08 g therefore the mystery metal is Ca!
3. The question is now asking us to find molar mass of the sulfide of this metal (CaS)
------> (40.08 g.mol-1)+ (32.06 g.mol-1) = 72.16 g.mol-1