Fundamentals Problem E15

[AhYeon_Kwon_2H]

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?

Please help! :( I'm not sure where the sulfide is coming from. I don't quite remember what metal hydroxide has to do with sulfide.

Thank you! :)

[Nicolette_Canlian_2L]

I first found the molar mass of the (OH)2, and then I subtracted this value from the given molar mass. This will give you the molar mass of the metal. Then, you must add the molar mass of the metal to the the molar mass of the sulfide ion to find the mass of the sulfide of this metal. Let me know if this makes sense or not

[yea-lyn pak_1G]

In this problem, the metal hydroxide is notated as M(OH)2 because we don't know what the metal is; M(OH)2 is basically some metal with the hydroxide (OH). When the problem asks for the molar mass of the sulfide of the metal, it's asking for the molar mass of MS. Basically, the sulfide (S) is replacing the hydroxide (OH). The metal, however, is the same. I hope this helps!

[Sophia Ding 1B]

I was also confused by the use of M and the word sulfide appearing without being in the equation; for a further clarification the M is just a variable for the "mystery element" they want you to find by subtracting the molar mass of (OH)2 from the given mass. From there, you find the mass of the metal sulfide by taking the molar mass of the mystery element you find plus the mass of sulfate to form the compound of MS, a metal sulfide.

[AhYeon_Kwon_2H]

Oh okay! That was helpful, thank you! :)