Gases, Liquids, and Solids Flashcards
Pressure
Force/unit of area
Gas properties
- Take the shape of the container
- No definite shape
- No definite volume
- Least dense phase of a substance
Standard pressure
1 atmosphere, 101.3 kPa, 760 torr, 760 mm Hg
Boyle’s Gas Law (movable piston)
P1V1 = P2V2
- Indirect relationship
- As pressure increases, volume decreases
- As pressure decreases, volume increases
Charles’ Gas Law
V1/T1 = V2/T2
- Direct relationship
- As temperature increases, volume increases
- As temperature decreases, volume decreases
What is important to remember about Charles’ law?
Temperature must be in Kelvin
Combined gas law
P1V1/T1 = P2V2/T2
Diffusion
The movement of gas particles from a region of high concentration to low concentration
Graham’s law of diffusion
v1/v2 = square root of m2/m1
v = velocity
m = mass
Which gas diffuses the fastest? Slowest? Why?
a) CO2 b) He c) N2 d) SO2
He diffuses the fastest because it has the smallest mass
SO2 diffuses the slowest because it has the largest mass
Dalton’s law of partial pressure
The total pressure in a room is equal to the sum of the partial pressures of the gases
Partial pressure setup for air
P total pressure of air = P N2 + P O2 + P Ar
How do you calculate partial pressure?
Moles of one individual gas x total pressure/sum of total moles
Characteristics of an ideal gas
- Gas particles are in constant, random, straight line motion
- Gases collide with each other and the walls of the container
- Gas particles are separate by great distances and have a negligible volume
- Gas particles do not attract each other
Which 2 gases behave most like an ideal gas?
Hydrogen and helium because they are the smallest elements with the smallest densities and radii. Helium is also inert.
Under which conditions does a gas become an ideal gas?
High temperatures and low pressure
Liquid properties
- More dense than gas phase, but less dense than solid phase
- Takes shape of container
- Definite volume
Vapor pressure
In a closed system, the vapor formed from the evaporation of a liquid or the sublimation of a solid that exerts a pressure on the walls of the container
What happens to vapor pressure as temperature increase?
As temperature increases, vapor pressure increase
If particles have a high vapor pressure and escape easily to the gas phase, they have…
Weak bonds or intermolecular forces
Intermolecular forces
Forces between molecules
If particles have a low vapor pressure, they have…
Strong intermolecular forces
Boiling point
The temperature at which the vapor pressure of the liquid or solid is equals to the external air pressure around it
Normal boiling point
The temperature at which vapor pressure equals standard pressure
