Problem E.9 in textbook

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Gisselle Sainz 2F
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Joined: Wed Feb 21, 2018 3:00 am

Problem E.9 in textbook

Postby Gisselle Sainz 2F » Sun Apr 08, 2018 5:19 pm

Epsom salts consist of magnesium sulfate heptahydrate.
a) how many atoms of oxygen are in 5.15 g of Epsom salts?

How do we solve this?

AshleyLamba1H
Posts: 30
Joined: Fri Apr 06, 2018 11:03 am

Re: Problem E.9 in textbook

Postby AshleyLamba1H » Sun Apr 08, 2018 5:53 pm

Firstly, you must find the formula for magnesium sulfate heptahydrate. The formula is MgSO4 · 7 H2O. To find the mass of this molecule, you must add up the molar masses of the individual atoms in the molecule, which gets you 246.48 g/mol. Knowing this will help you find the number of atoms that are in 5.15 g of Epsom salts.

Susu Le 1F
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Re: Problem E.9 in textbook

Postby Susu Le 1F » Sun Apr 08, 2018 6:17 pm

Using the molar mass of magnesium sulfate heptahydrate (246.48 g/mol) above, you can find the number of moles in 5.15 g of Epsom salts. Once you have the number of moles of Epsom, you can find the number of moles of Oxygen. Finally, you can calculate the number of atoms of oxygen using Avogadro's number.

Carissa Young 1K
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Joined: Fri Sep 28, 2018 12:17 am

Re: Problem E.9 in textbook

Postby Carissa Young 1K » Wed Oct 03, 2018 10:52 pm

use molar mass to find out the moles of the Epsom salts
5.15 g H14MgO11S / 246.466 g*mol^-1 = .02089 mol H14MgO11S

use the ratio of 11 mols oxygen to 1 mol of Epsom salts and then multiply by Avogadro's number to find how many atoms of oxygen
.02089 mol H14MgO11S * (11 mol O / 1 mol H14MgO11S) *(6.022 * 10^23)
= 1.38 * 10^23 atoms of O


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