How to multiply chemical compounds together?

[PhizKid]

Homework Statement

$CuSO_4 \cdot 5H_20$

Homework Equations

The Attempt at a Solution

We never learned this. I don't even know what it means to "multiply" compounds together...doesn't make any sense to me

 

[Simon Bridge]

In what context are you seeing this notation?

I suspect what you are seeing is the notation for a hydrate - a copper-sulphate crystal with water in it.

 

[PhizKid]

it says to find the mass of each element. then that formula is given

 

[SteamKing]

If you give a complete problem statement, your chances of receiving help will increase.

 

[Simon Bridge]

Well ... that notation normally means that each copper-sulphate molecule has 5 water molecules associated with it in the lattice. Copper-sulphate is a penta-hydrate ... heat the crystal and you see steam comes off, and you end up with anhydrous copper sulphate, which is a white powder. The water gives it that characteristic blue rhomboid crystal.

it says to find the mass of each element. then that formula is given

That's the raw question - but what is the context?
You are doing a chemistry course and they have reach a particular topic involving...
The mass of each element ... present... in a crystal ... in a particular concentration of solution...

Anyway:
The penta-hydrate copper sulphate compound would have 9 oxygen atoms for example... 5 from the water and 4 from the copper-sulphate.

http://en.wikipedia.org/wiki/Copper(II)_sulfate
http://en.wikipedia.org/wiki/Hydrate

 

[NascentOxygen]

Homework Statement

$CuSO_4 \cdot 5H_20$

I believe this has been well explained. The dot and the right side represents the water of crystallisation.

If you need to mix a 1M solution of copper sulphate, you need to know how much to weigh out. It is important that you calculate the weight based on CuSO₄•5H₂O and add that to a flask of water then top it up to the 1 litre mark.

Your solution would not be 1M if you kept to the formula CuSO₄ when using blue crystals of copper sulphate (these being CuSO₄•5H₂O, the common form of copper sulphate).