Ideal Gas Law Help

Question

At 0°C and 760 mm Hg, 28 grams of nitrogen occupy 22.4 liters. Compute the mass of one liter of nitrogen at 35.0°C and 1500 mm Hg.

Answer 1

PV = nRT

n = (1.97*1)/(0.082*308) 1.97 atm = 1500 mmHg 308K = 35°C

n = 0.078 mols of N₂

m = 0.078*28

m = 2.18 g

Answer 2

So Ivan M.,

You could employ the Ideal Gas Law. You are given : p, V, n, and T (well, you can calculate in absolute temperature by now, I hope?). So you determine R. That's your universal gas constant, and it has different values for each set of units in which it is expressed (0.08205 L atm mol^-1 K^-1 , etc.)

Then apply it to the new conditions: different V, T, and p, but same R. What's not to like about a new n (from which you darn well better be able to calculate mass, using a Periodic Table)?

OR if you get good, you can just start ratioing from the first set of parameters to the second. In your head, pick out whether you have to do "new/old" or "old/new" for each multiplication. So if you go UP on temperature, the mass involved would go DOWN. So do *(old/new) for that parameter. And so on.

(I know, actually they aren't parameters, they're variables. The usage for "parameter" varies across disciplines, look it up sometime).

-- Cheers, --Mr. d.