problem e15 "sulfide of this metal"

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Andrea- 3J
Posts: 56
Joined: Tue Nov 14, 2017 3:00 am

problem e15 "sulfide of this metal"

Postby Andrea- 3J » Thu Oct 04, 2018 1:29 am

E15 "The molar mass of the metal hydroxide M(OH)2 is 74.10 g/mol. What is the molar mass of the sulfide of this metal?"
I need clarification with this problem. I am assuming M stands for the unknown metal sulfide. So the total molar mass of M(OH)2 which is S(OH)2 is 74.10g/mol.
O=16g
H=1.008g
16(2)+1.008(2)=34.016
74.10-34.016=40.084g
The molar mass of the sulfide is 40.084g/mol.
Is my solution/ process correct?

Seohyun Park 1L
Posts: 73
Joined: Fri Sep 28, 2018 12:29 am

Re: problem e15 "sulfide of this metal"

Postby Seohyun Park 1L » Thu Oct 04, 2018 1:32 am

The 40.48 g/mol is for the metal of the compound (which is Ca). If you take the sulfide of Ca, it would be CaS, so you would need to add the molar mass of sulfur to the molar mass of Ca, getting a final answer of 72.15 g/mol.

A De Castro 14B 2H
Posts: 75
Joined: Fri Sep 28, 2018 12:29 am

Re: problem e15 "sulfide of this metal"

Postby A De Castro 14B 2H » Thu Oct 04, 2018 9:37 am

I believe that your process is correct, Andrea. However, I rounded my answer to 40.08 gmol-1 because the question started with 4 significant figures. Also, since the molar mass is 40.08 gmol-1, the metal would be calcium.


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