[Reviction]

Here is the problem:

A gas of unknown molecular mass was allowed to effuse through a small opening under constant pressure conditions. It required 113 s for 1.0 L of the gas to effuse. Under identical experimental conditions it required 31 s for 1.0 L of O2 gas to effuse. Calculate the molar mass of the unknown gas. (Remember that the faster the rate of effusion, the shorter the time required for effusion of 1.0 L; that is, rate and time are inversely proportional.)

113s/31s=sqroot(32g-mol / x)
sqroot(113s/31s)=31g-mol/x
x * 1.90923 = 32g-mol
=16.76 (Have not rounded yet)

Problem 2
Many gases are shipped in high-pressure containers. Consider a steel tank whose volume is 63.0 L and which contains O2 gas at a pressure of 1.46E4 kPa at 29.8°C.

(a) What mass of O2 does the tank contain?

PV/RT = 144.09*63.0 / .08206*302.8k = 365.33 mols O2

(b) What volume would the gas occupy at STP?

nRT/P=(.08206)(365.33)(273) / 1 atm = 8184.2615L

(c) At what temperature would the pressure in the tank equal 1.60E2 atm?

PV/nR = 1.60E2atm * 63L / 365.33mols*.08206 = 336.2k


Sorry alot to read but thanks guys. I just wasnt sure if I had the correct moles on #2 and I haven't rounded them yet.

[Sev]

(a) What mass of O2 does the tank contain?

PV/RT = 144.09*63.0 / .08206*302.8k = 365.33 mols O2

Question asks for mass, not moles.

[Padfoot]

113s/31s=sqroot(32g-mol / x)
sqroot(113s/31s)=31g-mol/x

You can't just throw the 'sqroot' over the other side.
This is wrong, continue from here:
(113/31)²=32/x

[Reviction]

So on A, would I covert the moles to grams? 325moles * 32?

Also on problem b, I square it then get rid of the 31 on the other side to find X? Thanks guys

[Padfoot]

So on A, would I covert the moles to grams? 325moles * 32?

Yes, but remember you have 365.33 mol.

Also on problem b, I square it then get rid of the 31 on the other side to find X? Thanks guys

'Get rid of' - you don't mean just delete it do you...
You have to rearrange the equation:
(113/31)²=32/x
32/(113/31)²= x

[Reviction]

Sorry I'm a texan with bad grammer Yea I ment what you put pad. Thanks alot for your help. Owe you one

[laxplayer]

I had this same problem, but it was 57s for the unknown gas to effuse, and 27s for O2 to diffuse. I plugged my numbers into the equation

You have to rearrange the equation:
(113/31)²=32/x
32/(113/31)²= x

So I had 32/(57/27)² and got 1.780055402, but It says I got it wrong. Do you know if there was anything I did wrong?

[Padfoot]

So I had 32/(57/27)² and got 1.780055402, but It says I got it wrong. Do you know if there was anything I did wrong?

You didn't read the calculator's answer properly.
(It actually reads 7.180055302).

[laxplayer]

oh, thanks!