# Gases and Atmospheric Pressure

Topics: Ideal gas law, Gas, Pressure Pages: 4 (809 words) Published: January 4, 2014
Gases and Atmospheric Pressure

Three types of motion and kinetic energy
-particles in a substance have three type of motion and therefore three types of kinetic energy -vibrational motion
-vibreational kinetic energy
-all particles have this type of energy
-rotational motion
-rotational kinetic energy
-particles in liquid and fases have some solids have this energy type -translational motion
-translational kinetic energy
-only particles in liquid and gas have this type of energy
Gases and Pressures Changes
Pressure
-recall: pressure id the force that is exerted on an object perunit of surface area -formula: pressure = force/area OR P = F/A
-the SI unit for force is newtons (N) and unit for area is square meters (m2) -therefore pressure has a unit of N/m2
-other units of pressure
-Pascal (Pa)
-millitetres mercury (mmHg)
-atmosphere
Atmospheric Pressure
-the gas molecules in our atmoshpere are pulled down towards earth's surface by gravity -these molecules exert pressure on all objects on earth
-earth's atmospheric pressure is therefore the force* that a column of air that exerts on earth's surface, divided by the area of earth's surface at the base of the column -therefore the force that the column of air exerts is its *weight -force is exerted equally in all directions

Atmospheric Pressure (atm)
-atmospheric pressure is how much pressure is being applied to something at sea level -column of air extending from sea level to the top of the atmosphere -cross-sectional area of 1m2
-mass of thie column of 10329 kg
-therefore, it weighs (force) 101325 N (because 10239 kg x 9.81 m/s2) -pressure = force/area
=101235 N/1 m2
=101235 N/m2
-therefore 101325 N/m2 will be equal to 1 atm
-this is the same concept as moles where 6.02 x 1023 particles = 1 mol Atmospheric Pressure and Altitude
-at high altituds, the atmospheric pressure is lower
-this is because the column pf air is smaller and therefore weight less -therefore...

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