Figuring out formula from looking at name

[leroyjenkens]

For example, is there any way to know that aluminum sulfate has the formula of Al₂(SO₄)₃ just by looking at the name "Aluminum Sulfate"? It seems like while doing chemistry problems, the problems kind of assume you can do that.

Thanks.

 

[CompuChip]

Well, aluminium ions are Al³⁺ and sulfate is (SO₄)^2-. So the only way to combine them and get something neutral back, is in the ratio 2 : 3.

 

[Entropee]

Right, so Al₂ makes it now a +6 charge and (SO₄)₃ will have a -6 charge. But you do in fact need to remember Al is Aluminum and SO₄ is Sulfate. But as far as the charges, we were always allowed to look at the periodic table for those. We had a whole week where we just memorized different things like carbon dioxide, water, methane, ethane, oxalate, sulfate, sulfite, etc. If you weren't required to do so I would suggest doing it anyways, it makes chem WAY easier.

 

[leroyjenkens]

Thanks for the responses guys.

We had a whole week where we just memorized different things like carbon dioxide, water, methane, ethane, oxalate, sulfate, sulfite, etc. If you weren't required to do so I would suggest doing it anyways, it makes chem WAY easier.

Is there like a list of all of them somewhere for me to study? What are they called? I'll go look it up.
I do need to learn that stuff, because when I see "sulfate" all I know is it's sulfur.

 

[Entropee]

I didn't actually watch this video lol, but I am sure it will be helpful. If not, basically everything you need to remember is on the board behind him. Except I don't think methane was on his list, which is CH4. If you need any more help just ask.

 

[leroyjenkens]

Awesome, thanks. This forum is making me more and more un-retarded every day.

 

[Entropee]

Yeah no lie, I'm going to ask so many math questions when i get to precalc (I suck at math) although this college algebra stuff is easy so far.

 

[leroyjenkens]

I wrote all of those down, but I noticed they're all charged molecules. Is there a reason for that? You mentioned methane isn't on the list, and since it's not charged, maybe that's why.

 

[Borek]

charged molecules

They are called ions

--

 

[Entropee]

Yes they are but remember a lot of times you have to combine them with ions and anions and balance them out. Also what borek says is correct but I believe many of them have negative charges too (anions).

 

[The-Exiled]

Also what borek says is correct but I believe many of them have negative charges too (anions).

Just to clear things up... Ions with a positive charge are called cations and ions with a negative charge are called anions (As you rightly said).

:)

 

[Entropee]

Ah yes forgive me, I forgot they were called cations, been a while now.