Question

what is the molecular weight (molar mass) of gas with a density of 4.72 g/l at 124 celsius and 426 torr?

Answer 1

@wolfe8

Answer 2

the choices are 316 g/mol
274 g/mol
282 g/mol
85.7 g/mol

Answer 3

i got 282 idk how

Answer 4

Well, you will have to use the formula PV=nRT. But you will have to convert the pressure to atm and temperature to Kelvin, and use R for Kelvin. Rearrange that so have every info you have on one side and what's left on the other side. Does that make sense?

Answer 5

a little so would i plug in 0.560526316 atm into p? and 397.15 into t?

Answer 6

Yes. And what is the equation you have? (after rearranging as I said)

Answer 7

0.56atmmmmm*397.15=what would be the n and r though im not sure?

Answer 8

We don't know n but R is 0.082

Answer 9

oh so the equation would be 0.56atmmmmm*v=n*0.082*397.15kelvin

Answer 10

So please rearrange it to have all the unknowns on the left side.

Answer 11

v/n=0.56atm*0.082*397.15kelvin is this right?

Answer 12

You can simplify that more haha. But now if you notice, what you have is volume over n. You are given mass over volume(density). How can you obtain mass over n? Hint: cancelling out.

Answer 13

hang on im writing this down

Answer 14

i was watching a youtube video earlier and it said that the r is 8.314 im confused

Answer 15

Well the R depends on what units you use for the others. If you notice, for 8.314 the unit is J/mol*K whereas what I have been showing is for when you use pressure instead of energy.