mak10 Posted November 16, 2004 Share Posted November 16, 2004 flask X contains 1 dm3 of helium at 2 kPa pressure and flask Y contains 2 dm3 of neon at 1 kPa pressure. if the flasks are connected at constant temperature, what is the final pressure? any ideas on how to solve this?? -mak10 Link to comment Share on other sites More sharing options...
swansont Posted November 16, 2004 Share Posted November 16, 2004 At constant T, PV is also constant. In a mixture, partial pressures add to be the total pressure. Link to comment Share on other sites More sharing options...
mak10 Posted November 16, 2004 Author Share Posted November 16, 2004 partial pressures added gives 3 kPa... but the correct answer is different. -mak10 Link to comment Share on other sites More sharing options...
jdurg Posted November 16, 2004 Share Posted November 16, 2004 Correct. That's because the overall volume has changed. So if you use P1V1 = P2V2 you can calculate the pressure of each gas at the new volume. Then you add up the partial pressures and you have your answer. (I got 4/3 kPa.) Link to comment Share on other sites More sharing options...
mak10 Posted November 16, 2004 Author Share Posted November 16, 2004 i still dont get it. whats the new volume? how did you get it? your answer is correct.... it is 4/3 kPa... but can you show me, briefly, the exact steps you took to get this answer? am confused... thanks jdurg! -mak10 Link to comment Share on other sites More sharing options...
jdurg Posted November 16, 2004 Share Posted November 16, 2004 i still dont get it. whats the new volume? how did you get it? your answer is correct.... it is 4/3 kPa... but can you show me' date=' briefly, the exact steps you took to get this answer? am confused... thanks jdurg! -mak10[/quote'] Sure. According to your initial post, the total volume will be 3 dm^3. This is what you get by adding the volume of gas 1 to the volume of gas 2. Since the flasks are connected, the overall volume will be the sum of the volume of the two flasks. To get the pressures, I just used P1V1 = P2V2 and figured out the new pressure of each gas. Gas X; (2kPa)(1 dm^3) = P2(3 dm^3). P2 = 2/3 kPa. Gas Y; (1kPa)(2 dm^3) = P2(3 dm^3). P2 = 2/3 kPa. So the partial pressure of each gas is 2/3 kPa. The total pressure is the sum of the partial pressures, so you just add the two partial pressures and get 4/3 kPa. Link to comment Share on other sites More sharing options...
mak10 Posted November 16, 2004 Author Share Posted November 16, 2004 ingenious... thanks a lot jdurg! -mak10 Link to comment Share on other sites More sharing options...
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