Dalton's Law and Partial Pressure

[Soaring Crane]

1) Determine the total pressure (in atm) inside a 83.00L cylinder containing 5.00 mole of nitrogen, 6.00 mole of oxygen, and 5.00 mole of argon at 417.00 kelvin.

P_total = (n1 + n2 + n3)*(RT/V)
P_total = (5.00 + 5.00 + 6.00 mol)*(0.08206*417.00 K/83.00 L) = 6.60E0 atm?? (correct sig. digits?)

2) Determine the partial pressure of nitrogen in a 6.00 L cylinder that contains 0.600 moles of oxygen, 0.600 moles of nitrogen, 0.800 moles of hydrogen, and 1.000 moles of helium at 340.00 kelvin.

P_N = X_N*(P_total)

X_N = (0.600 mol N)/(0.600 N + 0.600 mol O + 0.800 mol H) = 0.300

P_total = (0.600 + 0.600 + 0.800 mol)*(RT/V)

P_total = (2.000 mol)*(0.08206*340.00K/6.00 L) = 2.000 mol*(4.6501) = 9.30 atm

P_N = 9.30 atm(0.300) = 2.79E0 atm ? (correct sig. digits?)

Thank you.

 

[Soaring Crane]

Are my calculations correct?

Thank you for any replies.

 

[andrewchang]

Yes, they are both correct

 

[Soaring Crane]

For #2, I just realized that I forgot to include the 1.000 mol He!


Now, is it this?

P_N = X_N*(P_total)

X_N = (0.600 mol N)/(0.600 N + 0.600 mol O + 0.800 mol H + 1.000 mol He) = 0.200

P_total = (0.600 + 0.600 + 0.800 mol + 1.000 mol)*(RT/V)

P_total = (3.000 mol)*(0.08206*340.00K/6.00 L) = 3.000 mol*(4.6501) = 13.95020 atm

P_N = 13.95020 atm(0.200) = 2.79E0 atm ? (correct sig. digits?)

Yet somehow I get the same answer!

 

[andrewchang]

(I didn't check your work- I only checked your answers. )