Lesson 45 Temperature and Gas Laws

Heat is the random motion of atoms and particles.

Temperature can only be measured in terms of its effects.

0 degrees celsius - water freezes
100 degrees celsius - water boils

32 degrees fahrenheit - water freezes
212 degrees fahrenheit - water boils

Temperature also affects pressure. Pressure is the force per unit area exerted.

Pressure = force/area

A molecule changes momentum when it exerts force on the wall of a balloon. The opposite forces results in the expansions of a balloon.

Heating a gas causes an increase in kinetic energy of the molecules, resulting in more pressure. The pressure of a gas is proportional to the number of molecules, inversely proportional to the volume, and proportional to the average kinetic energy of the molecule. The constant of proportionality is 2/3.

p = 2/3 (N/V) k

pv = constant if temperature is constant

p1v1 = p2v2 Boyle's Law
                           _
constant = 2/3 Nk

pv is proportional to the kinetic energy of all molecules of the gas. This kinetic energy is a form of heat. Heating a gas causes pressure to rise and volume to rise.

All gasses expand by the same amount with a given rise in temperature. At a given pressure the volume of gas changes by the same fraction for each degrees in temperature.

v1/t1 = v2/t2 Charles's Law

There exists a temperature so low that a gas would fill no volume. This temperature is known as absolute zero, where a gas has no heat.

Absolute zero is -273 degrees celsius, -459 degrees fahrenheit, and 0 degrees kelvin.

pv = knt determines the size of one kelvin where k = 1.38 x 10^-23 J/K

Kinetic Theory of Gasses

The kinetic energy of a gas, or the collective effects of molecular collisions, is what gives a gas pressure and volume.

Temperature and heat connection:
                     _
knt = (2/3) Nk

pv = knt
                   _
pv = (2/3) nk
                _
kt = (2/3) k - absolute temperature

Heat and temperature are related by kinetic energy of the molecules of gas.

Heat in a gas is the average kinetic energy of molecules.

Absolute temperature is (2/3) the mean average kinetic energy of one molecule of gas

pv = Nkt - all temperature and pressure are related by the ideal gas law, which leads to the kinetic theory.