What are some common mistakes students make when measuring gas pressure?

Question

Henry Antrim · Accepted Answer

Given the plethora of gas pressure units...mistakes are routine and inevitable...

One of the things I cannot account for is the persistence of the #"psi"#...#"pounds per square inch"#. What the f... is that? And there is also an issue with #"psi"#, and #"psig"#; the latter is #"pounds per square inch gauge"#, and the ZERO reading on this scale is #1*atm# or #"32 psi"#...And so a reading of #1-2*"psig"# is a bit over one atmosphere. I think these days the preferred pressure measurement is #"1 bar"#, where #"1 bar"# is almost an atmosphere... Chemists traditionally used the #"atmosphere"#, an accessible and meaningful unit...especially so as a mercury manometer could be set up to measure pressure AT or below #"1 atmosphere..."# And #1*atm-=760*mm*Hg#... Of course, these days the mercury manometer and the McLeod gauge have all but disappeared from modern laboratories. At least we won't die now!

Noah Aldrich · Answer

undefined Some common mistakes students make when measuring gas pressure include: 
1. Not ensuring the apparatus is properly sealed.
2. Using the wrong units or failing to convert units correctly.
3. Not allowing enough time for the pressure to stabilize before recording the measurement.
4. Mishandling the equipment, such as applying too much force when closing valves or adjusting knobs.
5. Failing to account for atmospheric pressure or not zeroing the instrument properly.
6. Not reading the pressure gauge or instrument correctly, leading to inaccuracies in the measurement.
7. Ignoring temperature effects on gas pressure, especially when using equipment that is sensitive to temperature changes.