Chapter 10 - Properties Of Gases Flashcards
Gas
A substance that has no well-defines boundaries but diffusés rapidly to fill any container in which it is placed
Which diffusés quicker between ammonia and hydrogen chloride
Lighter ammonia molecules diffuse quicker than heavier hydrogen chloride molecules
Properties of Gases
No fixed volume - take volume of container
Volume depends on temperature and pressure
Temperature
Measure of the degree of hotness of an object
0°C is equal to
273K
Pressure of a gas
The force the gas exerts on a unit area
Newtons per metre squared or pascals
1kPa is equal to
1000 Pa
Normal atmospheric pressure
100kPa
100,000 Pa
1 litre is equal to
1000cm^3
Standard Temperature
273K
0°C ~ freezing point
Standard pressure
100,000 Pa
100 kPa
Boyle’s Law
At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure
pV=k
Charles’ Law
At constant pressure, the volume of a fixed mass of gas is directly proportional to its temperature measured on the Kelvin Scale
k = V/T
Combined Gas Law
p1V1 = p2V2
–––– –––––
T1 T2
- Convert to Kelvin
- Consistent units
Gay-Lussac’s Law of Combining Volumes
In a reaction between gases,
The ratio between the volumes of the reactant gases
and the gaseous products
can be expressed in simple whole numbers
Provided the volumes are measured at the same temperature and pressure
Avogadro’s Law
Equal volumes of gases contain equal numbers of molecules under the conditions of temperature and pressure
One mole of a gas occupies
22.4L
Assumptions of the Kinetic Theory of Gases
- Gases are made up of particles in continuous rapid, random motion
- No attractive or repulsive forces between the molecules of a gas
- Gas molecules are so small and widely separated that the volume of all the molecules is tiny compared to the spec they occupy
- The collisions are perfectly elastic
- Average kinetic energy of molecules is proportional to temperature on Kelvin scale
Limitations of the Kinetic Theory of Gases
- All real gases DO have tiny attractive forces between the molecules .e.g. ammonia
- Under high pressure when molecules are crowded together, the volume is not tiny compared to the distance between them
Ideal gas
One that perfectly obeys all the assumptions of the kinetic theory of gases under all conditions of temperature and pressure
Real gases
Forces of attraction and repulsion do exist between the molecules
The volume of the molecules is not negligible
Rapid movement of tiny particles in a liquid or gas
Brownian motion
When do gases depart from ideal behavior
High pressure and low temperatures, molecules are close together and moving slowly
