Textbook Problem E.15  [ENDORSED]

Moderators: Chem_Mod, Chem_Admin

Posts: 105
Joined: Wed Sep 30, 2020 9:47 pm
Been upvoted: 2 times

Textbook Problem E.15

Postby MHarrold_1E » Mon Oct 12, 2020 9:57 am

Could someone walk me through the steps to solve this problem...

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?

Sophia Hu 1A
Posts: 113
Joined: Wed Sep 30, 2020 10:09 pm
Been upvoted: 8 times

Re: Textbook Problem E.15  [ENDORSED]

Postby Sophia Hu 1A » Mon Oct 12, 2020 10:03 am

Since you know (OH)2 is part of the metal hydroxide you can find that molar mass which is 34.02 grams/mol. You are given that teh entire metal hydroxide molar mass is 74.10 grams/mol.

74.10 grams/mol - 34.02 grams/mol = 40.08 grams/mol

This molar mass is the molar mass of Ca.

Therefore, the metal hydroxide would be Ca(OH)2

The problem asks you to find the molar mass of the sulfide of this metal: CaS

40.08 grams/mol + 32.06 grams/mol = 72.14 grams/mol of CaS

Samudrala_Vaishnavi 3A
Posts: 93
Joined: Wed Sep 30, 2020 9:34 pm

Re: Textbook Problem E.15

Postby Samudrala_Vaishnavi 3A » Tue Oct 13, 2020 8:22 am

To put it simply, this problem is asking you to basically find a type of metal, add sulfur to that metal, and then find the molar mass of that metal and the sulfur.
1.) subtract the molar masses of hydrogen and oxygen from the total molar mass given.
2.) find an element on the periodic table that has the same/ closest molar mass to what you found from subtraction in Step 1.
3.) Add a sulfate to this.
4.) Calculate the molar mass of element found and the sulfate. (Add together since they are a compound)

Thomas Gimeno
Posts: 75
Joined: Wed Sep 30, 2020 9:49 pm

Re: Textbook Problem E.15

Postby Thomas Gimeno » Sun Oct 18, 2020 10:10 pm

Well the first step is to identify what the sulfide would look like. Because Ca would give up its two valence electrons it has a charge of +2. Sulfur wants to gain two electrons to fill its outer shell which makes it -2. This means the Calcium Sulfide is just CaS. To then find the molar mass you can just add the molar mass of calcium to that of sulfer.


Return to “Accuracy, Precision, Mole, Other Definitions”

Who is online

Users browsing this forum: No registered users and 1 guest