Oxygen Tank Problem/Ideal Gas Law - solving for pressure

[~anne~]

Problem: A cylinder of compressed Oxygen is carried on a spacecraft headed for Mars. The
compressed gas cylinder has a volume of 17000 L and is filled to a pressure of 157
atm at 234 K. The maximum pressure the cylinder can hold is 1000 atm.

Question: The contents of the cylinder are then entirely transferred to a partially filled holding
tank of volume 10,000 L, originally at pressure 22 atm and 300 K. What is the new
pressure in the holding tank at 300 K?

Relevant equation: PV=nRT

Attempt at Solution (hopefully it's quite clear enough to tell for where the error is):

I first solved for number of moles in the tank
--> n=PV/RT= (2228977 Pa)(10 m^3) / (8.31 J/molK)(300 K) = 8940.942639 moles

I then solved for the previous number of moles from the cylinder with 17000 L
---> n= PV/RT= (101325 Pa)(0.01764 m^3) / (8.31 J/molK)(294 K) = 0.7315884477 moles

I added both of these to get the total number of moles in the new tank and then solved for the new pressure
-----> P=nRT/V = (8941.674228 moles)(8.31 J/molK)(300K) / (10 m^3) = 2229159.385 Pa

This is the same as before in atm - 22 atm. I don't understand how I'm getting the same answer. Is there an error in how I calculated the initial number of moles before the transfer? Please specify. Thanks in advance!

SORRY! Seems there actually was a mistake in my initial calculation (typing it out here helped me reflect). I was confusing the calculations from two different problems. I redid the problem correctly and did it right this time.

 

[jbsteele]

I first solved for number of moles in the tank --> n=PV/RT= (101325 Pa)(10 m^3) / (8.31 J/molK)(300 K) = 3739.108531 molesI then solved for the additional number of moles from the cylinder with 17000 L---> n= PV/RT= (157 atm)(0.01764 m^3) / (8.31 J/molK)(294 K) = 11.71808721 molesI added both of these to get the total number of moles in the new tank and then solved for the new pressure-----> P=nRT/V = (3751.82644 moles)(8.31 J/molK)(300K) / (10 m^3) = 2230354.328 PaThis is the same as before in atm - 223 atm.