## E15 homework problem

melissa_dis4K
Posts: 106
Joined: Fri Sep 28, 2018 12:28 am

### E15 homework problem

On question E15, the question says: "The molar mass of the metal hydroxide M(OH)2 is 74.10 gmol1. What is the molar mass of the sulfide of this metal?" I got confused that it said "sulfide" does anyone know what that refers to in the formula?

Julia Go 2L
Posts: 60
Joined: Sun Sep 30, 2018 12:17 am
Been upvoted: 1 time

### Re: E15 homework problem

In this problem, the metal M is unknown and you need to figure out what it is. You know that the molar mass of the molecule is 74.1 and you can calculate the molar mass of the hydroxide, which turns out to be 34.02 g/mol. So to find the mass of the metal you do:

M = 74.1 g/mol - 34.02 g/mol = 40.08 g/mol

Look at the periodic table to figure out which element has a molar mass of 40.08 g/mol. The "sulfide" part of the question is basically asking you to find the molar mass of MS. (M = unknown metal M) (S = sulfur)

melissa_dis4K
Posts: 106
Joined: Fri Sep 28, 2018 12:28 am

### Re: E15 homework problem

Thanks, this helped!