PV = nRT, or 22.4L?

Question

Problems involving gases can be solved using

PV = nRT

or by using 22.4L as the volume of 1 mol at STP, and

P1V1/T1 = P2V2/T2

Which do you think is better (of course, they come down to the same thing in the end), and why?

Answer 1

I prefer the Combined Gas Law, I like to lay it all out neatly and indicate the units.
If any one of the variables is Constant, then I use the relevant Law of Boyle, Charles or Gay Lussac, which are easier still.

I do use the other choices from time to time but, still prefer the above.

Answer 2

The 22.4L/mol have been already calculated from pV=nRT and if you have environmental conditions differnent from STP then you need PV=nRT .
As well P1V1/T1 = P2V2/T2 comes from the general gas equation : (PV)/T=nR , if you don't change n then you can say (PV)/T=constant....
So all the same and depending on the problem you are faced.

Answer 3

sometimes 22.4L is better because you don't have to look up R for whatever units you're using.

Either way works since

PV = nRT

nRT/P = V

for n = 1 mole, R = .0821 L atm/moleK, P = 1 atm, T = 273.15K, -----> V = 22.4 L

ie, 1 mole at STP = 22.4 L

either way. your choice

Answer 4

fairly consumer-friendly back, get the right gadgets and plug it in to PV = nRT. discover your moles, and then use that to discover the molar mass. Convert your gadgets: 224 ml = 0.224 L; fifty 5 deg C = 328.15 ok; 886 torr = a million.17 atm (760 torr / atm) (a million.17 atm)(0.224 L) = n(0.08206 L?atm?ok?a million?mol?a million)(328.15 ok) n = 9.73E-3 mol Use 0.0388 g and 9.73E-3 mol to discover the molar mass: 0.0388 g / x = 9.73E-3 x = 4.0 g / mol (sig. figs back); so which you have Helium gas.

Answer 5

Damn I can't compete with 3 top contributors in that! But I can assure that I can lean more toward m v's answer!