Gases and Kinetic Theory COPY Flashcards
What was used to see Brownian motion?
Smoke particles with a microscope
What is Brownian motion?
Where particles seem to be wriggling unpredictably.
How did Brownian motion show the existanceof molecules and atoms?
The unpredictable wriggling is due to being bombarded unevenly and experiences forces due to these impacts, which changes its magnitude and direction.
What is pressure caused by?
The molecules in a gas bombarding the walls of the container
What does the graph of pressure against temperature look like?
Define absolute zero
The temperature where the pressure of an ideal gas becomes 0
Draw the graph of pressure against volume
Draw the graph of pressure against 1/volume
How would you use an experiment showing Boyle’s Law to show that P is directly proportional to 1/V
What is Boyle’s Law?
P is directly proportional to 1/V
How would you use an experiment showing Charles’s Law to that volume is proportional to temperature
What is Charles’s Law?
V is directly proportional to T
Explain how the experiment showing the pressure Law and be. used to prove P is directly proportional to T
what does the pressure law show?
P is directly proportional to T
What is the molar mass?
The mass of one mole of a gas (Mr)
What is the molecular mass?
The mass of one molecule of the gas
Define mole
The number of atoms of C-12 in 12g of C-12
What are the three gas equations (moles)?
mass = mr x mol
N = Na x mass / mr
mol = N / Na
N = No. of molecules
Na = Avagadro’s Constant
What are the three arrangements of the ideal gas equation?
pV = nRT
P1V1 / T1 = P2V2 / T2
pV = NkT
Define an ideal gas
One which obeys the equation pV = nRT at all temperatures and pressures
What are real gases
Gases that behave like ideal gases at low pressures and temperatures above room temperatures
When does an expanding gas do no work?
When it is expanding into a vacuum
What is the equation for the work done by an expanding gas at constant temperature?
W = p∆V
Why does a gas exert a force on a wall?
- The gas molecules collide elastically with the walls of the container
- Their velocity will change direction but keep the same magnitude
- This causes the component of their momentum perpendicular to the wall to change
- By Newton’s second law the molecules must have a resultant force on them to cause this change in momentum
- This resultant force is exerted by the wall on the molecules
- By Newton’s third law, if the wall puts a force on the molecules, the molecules must put an equal opposite force on the wall
- The forces from all the molecules cause a pressure on the wall, which can be calculated by P = F / A