# Per cent

1. Jan 25, 2005

### danne89

Hi! How many per cent of NaF and AlF3 does Na4AlF6 consist of?

I get 20 % NaF, but that isn't correct. I've done such problems before, just this seems to be unusual. Can you maybe check my work.

Greatfull,
Danne

2. Jan 25, 2005

### dextercioby

Question:What is the structure (geometry and bonding) and oxydation numbers of this hexafluoroaluminate of sodium
$$Na_{4}AlF_{6}$$

Daniel.

3. Jan 25, 2005

### danne89

$$4 Na^-~ Al^{3+} ~ 6F^-$$
So the bonding between the F's and the Al is covalent. And the bonding between the Na's and the other group is ionic.

How do you write oxydation numbers in Latex? Anyway, it looks like this, I think:
Na_4 - -4
Al - +3
F_6 - -6

It can't be correct, though, for the numbers must equals zero.

4. Jan 25, 2005

### dextercioby

Yes,that's what i was insinuating.The compound doesn't exist as a molecule (it's not neutral).Therefore it makes no sense to discuss its "concentration" of other molecules...

Daniel.

5. Jan 25, 2005

### danne89

Spooky. I'll look it over some more times.

6. Jan 25, 2005

### Gokul43201

Staff Emeritus
I suspect, your original compound is cryolite ($Na_3AlF_6$), which is commonly used in the molten form for the electrolytic production of Aluminum.

$$Na_3AlF_6 \equiv 3NaF + AlF_3$$

PS : Na has oxid state = +1