## How many atoms, how many moles are in epsom salts?

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Kensharra D 3J
Posts: 7
Joined: Fri Sep 28, 2018 12:26 am

### How many atoms, how many moles are in epsom salts?

How do I solve this problem?:
Epsom salts consist of magnesium sulfate heptahydrate. Write its formula.
a) How many atoms of oxygen are in 5.15g of Epsom salts?
b) How many formula units of the compound are present in 5.15g?
c) How many moles of water molecules are in 5.15 g of Epsom salts?

ran2000
Posts: 66
Joined: Fri Sep 28, 2018 12:15 am

### Re: How many atoms, how many moles are in epsom salts?

Epsom salts consist of magnesium sulfate heptahydrate. Write its formula.
a) How many atoms of oxygen are in 5.15g of Epsom salts?
b) How many formula units of the compound are present in 5.15g?
c) How many moles of water molecules are in 5.15 g of Epsom salts?

Answers:
a) no. of moles of magnesium sulfate in 5.15g= 5.15/ 246.46= 0.0209 moles
Since there are 11 moles of oxygen in 1 mole magnesium sulfate. Hence, there are 0.23 moles of oxygen in 0.0209 moles magnesium sulfate.
Thus number of atoms= 6.022*10^23 * 0.23= 1.38*10^23 atoms oxygen.

b) No. of formula units is the same as the number of moles= 0.23 moles

c) Since there are 7 moles of water in 1 mole of Magnesium sulfate, there are 0.146 moles of water molecules in 0.0209 moles of magnesium sulfate.

Alex Alonso - 4F
Posts: 28
Joined: Fri Sep 28, 2018 12:27 am

### Re: How many atoms, how many moles are in epsom salts?

I attached a picture of my work for this problem, let me know if I need to clarify anything/if you can’t read my writing :)
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