Kientic Theory Flashcards
What is an ideal gas (2)
-an ideal gas is one that is thin enough and for away from condensing that the interaction between molecules is negligible
-ideal gases are so far apart from each other that the interactions between individual particles are negligible this means there are no attractive or repulsive forces between them
What does pressure of an ideal gas depend on (3)
Temperature
Number of molecules
Volume
State the equation of pressure (2)
Pressure = k x (no of particles x temperature/ volume )
K = 1.38 x 10-23
PV = nRT
What happens to the pressure if the volume of ideal gas is held constant (1)
Pressure increases with temperature
What happens to the pressure when the volume and temperature is kept constant but more gas is added such as inflating a tire (1)
Pressure increases
What happens to pressure when temperature is constant but volume decreases (1)
Pressure increases
State the boyles law and state an equation (2)
-the pressure varies inversely with the volume
-the curves of constant temperature are called isotherms
P1V1 = P2V2
State the Charles law and give an equation (2)
-the volume of a gas increases with temperature if the pressure is constant
Vi/Ti = Vf/Tf
State the formula to calculate the mass of an individual atom (1)
Atomic mass / 6.02 x 10^23
State and explain the kinetic theory (3)
-the kinetic theory relates microscopic quantities (position, velocity) to macroscopic one’s (pressure, temperature)
-gas molecule’s always obey newtons law
-collision between gas molecules and walls is elastic
Explain how the gas molecules collide (2)
-as a gas molecules moves around they collide with each other and with the walls of the container
-these collisions are elastic (meaning energy and momentum are conserved)
Define the pressure of the gas (1)
The pressure of the gas is the result of the average force per unit area due to all collisions with the container walls
What does the pressure of gas depend on (3)
-mass
-speed of molecules
-container size
What does the maxwell distribution graph explain (1)
-It describes the speeds and kinetic energies of particles in an ideal gas
What does the speed depend on (2)
Temperature
Mass of molecule
State the formula for average temperature and average KE (1)
1/2mv^2 = K = 3/2kT
Temperature needs to be in kelvin
The atmosphere has nitrogen and oxygen, is the rms speed of nitrogen (28g/mol) greater than less than or equal to oxygen (32g/mol) (3)
-since both the molecules are at the same temperature
-they have the same KE
-but nitrogen has a lower mass thus it will have higher speed
What is internal energy of a gas and state a formula (1)
-internal energy of an ideal gas is the sum of the KE and PE
U = 3/2 NKT
State the equation for monoatomic ideal gas (1)
U = 3/2 NKT
How does evaporation occur (2)
-some molecules at the surface of the liquid gain enough KE to overcome the attractive forces within the liquid
-and transition into vapor
-the process of evaporation is faster for lighter molecules
How does condensation occur (1)
-molecules in the vapor phase can loose energy and undergo condensation transitioning back into the liquid phase
How does dynamic equilibrium take place (3)
-as evaporation and condensation proceed
-the number of molecules transitioning from liquid to vapor equals the number transitioning from vapor to liquid
-equilibrium is reach when the number remains constant
When water boils on top of a mountain, does it boil at 100 ?
No
-because the air is thinner, hence less pressure at the top of the mountain thus lower than 100c needed to boil
-a liquid boils at the temperature at which it’s vapor pressure
When does a liquid boil (1)
-a liquid boils at the temperature at which it’s vapor pressure equals the external pressure
What happens to the process of condensation or evaporation if the container is open (2)
-the vapor will escape and continue to escape without reaching equilibrium
-as the molecules that escape from the liquid are the higher energy ones leaving behind low energy particles
Define latent heat and state an equation (3)
-it is the heat that must be added or removed from one kilogram of a substance to convert it from one phase to another
-during this process the temprature remains constant
Heat absorbed or released = mass of substance x specific heat of substance
