640 mm Hg and 22C unless otherwise specified.
STP: 760 mm Hg and 0C
To convert our barometer in mbar to mmHg use factor-label method.
= 640.55 mm Hg. (air pressure does change with weather systems)
To convert mmHg to mbar use factor-label again. Cool Huh!!!!?
= 911.93 mbar
K = C + 273
When working on gas laws, don't forget to use your common sense. You probably already know what will happen at the new conditions. Think of the balloon in a hot car going over the Sierra's
Boyle's Law: If you double the pressure, you will halve the volume.
Charles' Law: If you double the temperature you will double the volume.
Combined Gas Law: Depends on whether you got it hotter, or increased the pressure more? Both temperature and pressure can vary.
Ideal gas law: most gases are "nearly ideal". This works well over "small" temperature or pressure ranges for nearly all gases. The volume and pressure depend on the amount of gas and its temperature. You need R the gas constant (fudge factor) to make everything come out right.
R = 0.0821 (L · atm )/( K · mole)
Use atm of
The gas constant has a compound unit so that 3 of the 4 units will cancel (if your set-up is right) and you'll magically be left with the correct units! Spiffy.