E.9 on homework

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Tatiana 4B
Posts: 30
Joined: Fri Sep 28, 2018 12:28 am

E.9 on homework

Postby Tatiana 4B » Wed Oct 03, 2018 5:19 pm

How does one know which coefficient to put in front of the H2O unit when looking at a chemical formula. Ex. In question E9, Epsom Salt has a 7 in front of the H2O, how would we know that?

armintaheri
Posts: 68
Joined: Fri Sep 28, 2018 12:26 am

Re: E.9 on homework

Postby armintaheri » Wed Oct 03, 2018 5:22 pm

The question tells you that epsom salt consists of magnesium sulfate heptahydrate. The prefix hepta- means 7. If you weren't given the name of the compound or the chemical formula then you would have no way of knowing the coefficient for water.

Mahir_Hasan2C
Posts: 60
Joined: Fri Sep 28, 2018 12:25 am

Re: E.9 on homework

Postby Mahir_Hasan2C » Wed Oct 03, 2018 5:22 pm

Since it says hepta in front of hydrate, where I believe in Greek hepta means 7, we put 7 in front of H20.

joanneyseung22
Posts: 31
Joined: Fri Sep 28, 2018 12:15 am

Re: E.9 on homework

Postby joanneyseung22 » Wed Oct 03, 2018 11:41 pm

I am confused about how we would know that O4 is part of magnesium sulfate? Unless I looked it up, I wouldn't have known.
Are there certain suffixes and prefixes that are pertinent to the first exam regarding the review topics? Like -ate, -ite, -ide, etc.

Sean Reyes 1J
Posts: 67
Joined: Fri Sep 28, 2018 12:24 am

Re: E.9 on homework

Postby Sean Reyes 1J » Thu Oct 04, 2018 10:43 am

The prefix "hepta-" implies that there are 7 water molecules.
This would mean that the compound would be written, in its entirety, as:
MgSO4 ・ 7H20


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