Finding molecular formula of CHCl gas from pressure and mass

[magma_saber]

Homework Statement

A compound has the empirical formula CHCl. A 256 mL flask, at 373 K and 750. torr, contains 0.800 g of the gaseous compound. Give the molecular formula.

Homework Equations

Only equation i know that relates to this is PV=nRT.

The Attempt at a Solution

I have absolutely no idea.

 

[Redbelly98]

That's the right equation. Plug in all the numbers you can into it, and see what happens.

 

[magma_saber]

All that will give me is "n." what good does that do?

 

[Borek]

n and 0.8 g - combine these two numbers.

 

[magma_saber]

how does that give me the molecular formula? I'm still lost...

 

[Redbelly98]

The empirical formula is CHCl. Given that, what are the possible molecular formulas?

 

[Borek]

how does that give me the molecular formula? I'm still lost...

Check what it does give you. Very important property of substance.

 

[magma_saber]

n and 0.8 g - combine these two numbers.

By this do you mean add n and 0.8? If so then i get 0.808. now what?

 

[Borek]

No, I didn't told you have to add them. Look at the units - one is number of moles, second is grams. You can't add them just like that.

There is a very important property of each reagent that combines moles and grams, and is extensively used in all almost chemical calculations. Seems to me like you have calculated that 0.008 mole is 0.8 g. Can you calculate now mass of other number of moles of the same substance?