Pressure of Gases

Pressure is defined a Force per unit area.With gases the force comes from the gas molecules hitting the side of the container. Air pressure is measured with a barometer.

Gas pressure is a gauge of the number and force of collisions between gas particles and the walls of the container that holds them. The SI unit for pressure is the pascal (Pa), but other pressure terms include atmospheres (atms), millimeters of mercury (mmHg), and torr. The following is a list of all of the standard pressure in every unit for pressure.

1 Atm = 760 torr =760 mmHg = 101.325kPa = 101,325 Pa = 14.7lb/in²⁼29.92 inHg

From-http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/prs/def.rxml

"Atmospheric Pressure is defined as the force per unit area exerted against a surface by the weight of the air above that surface. The Diagram to the right , the pressure at point "X" increases as the weight of the air above it increases. The same can be said about decreasing pressure."

In the mountains there is less air above you so less pressure. Since gases are compressable, this creates an environment in the mountains that has less air per unit volume. It will be harder to breathe in the mountains because there is actually less O₂per volume compared to at sea level.

Examples-Highlight to reveal answers

	Set up		Answers
99.6 kPa to atm	99.6 kPa X	1 atm 101.3 kPa	= 0.983 atm

0.983 atm to mmHg	0.983 atm X	760 mmHg 1 atm	= 747 mm Hg

747 mm Hg to torr	747 mm Hg X	760 torr 760 mmHg	=747 torr

747 torr to kPa	747 torrX	101.3 kPa 760 torr	= 99.6 kPa

50.0 kPa to atm	50.0 kPa X	1 atm 101.3 kPa	= 0.494 atm

2.60 atm to mmHg	2.60 atm X	760 mmHg 1 atm	= 1976 mm Hg

315 torr to mmHg	315 mm Hg X	760 mmHg 760 torr	=315 mmHg

5.0 atm to kPa	5.0 atm X	101.3 kPa 1 atm	= 505 kPa

260 mmHg to atm	260 mmHg X	1 atm 760mmHg	= 0.342 atm

21.2 kPa to torr	21.2 kPaX	760 torr 101.3 kPa	= 159 torr