[beethove]

At 136°C and atmospheric pressure, the density of TiCl₄ is 5.6 g L^-1. Under the same conditions, the density of gaseous N is 0.83 g L^-1. Determine the molecular formula of TiCl₄.

ANSWER: TiCl₄

How? And the reasoning?  Thanks!

[Hunter2]

Express the density by using ideal gas equation. Calculate molecular mass with it.

[mjc123]

And remember that gaseous nitrogen is N₂, not N!

[beethove]

I did and the mole ratio is 1:1, which I guess is why the answer is TiCl4...but why do I even need to know the mole ratio between them figure out the molecular formula TiCl₄?

[Hunter2]

What mole ratio do you mean.

Confirm the molare mass from N₂

You have pV = nRT, n =m/M and Rho = m/V

convert this to M =?

The same you do with the Titanium chloride. The calculated molar mass you have to split in x Ti and y Cl^-.

[beethove]

I just got it.  Your method works.  Another way (and I think what the chapter was trying to test) was that density is proportional to molar mass. So, this also solves it:

5.6 g L^-1/0.83 g L^-1(28.0 molar mass N₂) = 189g of TiCl₄

Therefore, TiCl₄ is molecular formula.

[Hunter2]

Yes correctly.

[Borek]

Another way (and I think what the chapter was trying to test) was that density is proportional to molar mass.

Both approaches are perfectly equivalent and based on the same basic principles.