Ideal Gases Flashcards
What are the 4 properties of gases?
Volume
Temperature
Pressure
Number of molecules
Why does pressure occur?
1) gas molecules move randomly
2) they collide with the walls
3) they change momentum, a force occurs
4) as force=change in momentum/time
5) pressure = force/area
How does pressure change when increasing the temperature?
Molecules have a higher average speed due to having more kinetic energy
Collide with the walls more frequently
Collide with the walls harder - both of which result in pressure increase
How does increasing the volume effect pressure
Molecules hit the walls less frequently
Average speed stays the same but there is a longer distance to travel between collisions
Decrease in pressure
What is the relationship between pressure and volume
Volume of gas decreases if pressure increases
Experiment to do with pressure and volume
1) air trapped in a syringe
2) measure the volume of air (side of syringe)
3) measure the pressure - pressure gauge
4) plunger of syringe can be pushed, so the volume decreases if pressure increases
Pressure volume graph
Non-linear
Pressure is inversely proportional to 1/volume
What is the formula for pressure-volume
p1V1=p2V2
Units for pressure volume
No need to convert
What is the relationship between pressure and temperature
As the temperature of the gas increases, pressure increases
Experiment to do with pressure and temp
1) fixed volume of air trapped in metal sphere
2) measure the pressure of air - pressure gauge
2) temp of air - thermometer
4) beaker of water is on a Bunsen burner
5) as water is heated - air heats
Graph of pressure and temp
Linear
Not proportional
What happens with pressure and temperature if you repeat the experiment with different size spheres
Hits axis at same point = -273 (where all molecular motion stops)
Pressure/temp graphs
Always a straight line
Not possible to get colder than -273
-273 degrees is called ‘absolute zero’
What is the Kelvin scale
A scale of temperature beginning at absolute zero
-273 degrees will equal 0 kelvin
