Section 10-2: Pressure Pressure (P): the force per unit area on a surface Pressure = Force / Area Newton (N): SI unit of force

Section 10-2: Pressure To describe a gas fully you need to state four measurable quantities: Volume Temperature Number of molecules Pressure

Section 10-2: Pressure Gas molecules exert pressure on any surface with which they collide. Depends on volume, temperature, and number of molecules.

Section 10-2: Pressure Barometer: a device used to measure atmospheric pressure. Introduced by Evangelista Torricelli in early 1600s The height of the mercury in the barometer depends on the atmospheric pressure.

Section 10-2: Pressure Units of pressure Millimeters of mercury: atmospheric pressure is often measured by a mercury barometer and expressed in terms of the height of the mercury. (mm Hg) 1 mm Hg = 1 torr

Section 10-2: Pressure Atmosphere of pressure (atm): exactly equal to 760 mm Hg, this is the “atmospheric” pressure at sea level. Pascal: is the pressure exerted by a force of one Newton on an area of one square meter. SI unit of pressure kPa = 1 atm

Section 10-2: Pressure Standard Temperature and Pressure (STP): the standard conditions of exactly 1 atm of pressure and 0˚C. *know this!!*