In Kinetic Molecular Theory, particles in an ideal gas:
have no volume
have elastic collisions
are in constant, random, straight-line motion
don't attract or repel each other
have an average KE related to Kelvin temperature
Characteristics of Gases
Gases expand to fill any container with random motion and no attraction
Gases are fluids like liquids, no attraction
Gases have very low densities, no volume = lots of empty spaces
Characteristics of Gases
4. Gases can be compressed
5. Gases undergo diffusion and effusion in random motion
Always use absolute temperature (Kelvin) when working with gases.
Pressure = force/area
Pressure
Barometer measures atmospheric pressure e.g. mercurybarometer
Pressure
manometer measures contained gaspressure e.g. u-tube manometer
StandardTemperature and Pressure (STP)
0 degree celsius or 273 K
1 atm or 101.325 kPa
The relationship between the volume of a gas and its pressure was analyzed by RobertBoyle in 1662. He found that the volume of the gas decreases as the pressure exerted on it increases.
In Boyle's Law, the pressure and volume of a gas are inversely related, at constant mass and temperature.
In 1787, Jacques Charles studied the relationship between the volume and temperature of a gas using a balloon. He concluded that the volume of a gas is directly proportional to its temperature.
In Charles' Law, the volume and absolute temperature (K) of a gas are directly related at constant mass and pressure.
Gay Lussac's Law
The person who is credited with the determination of the temperature-pressure relationship in gases at constant volume is Joseph Louis Gay-Lussac.
He deducted that the pressure of a gas is directly proportional to its temperature.
Combined Gas Law
combines the 3 gas laws: Boyle's, Charles' and Gay-Lussac's Law
states that the ratio of the product of pressure and volume and the absolute temperature of a gas is equal to constant.
When Avogadro's Law is added to the combined gas law, the Ideal Gas Law results.
Unlike the named gas laws, the Combined Gas Law doesn't have an official discoverer. It is simply a combination of the other gas laws that works when everything except temperature, pressure, and volume are held constant.