gases kinetic molecular theory of gases. a gas consists of small particles (atoms/molecules) that...
TRANSCRIPT
A gas consists of small particles (atoms/molecules) that move randomly with rapid velocities
Further Information
They move faster when heated.
The attractive forces between particles of a gas
can be neglected
Do you think this is accurate?
Why would this be important for calculations?
The actual volume occupied by a gas molecule is
extremely small compared to the volume
that gas occupies.
Is this true in the real world?
Why would this be helpful with calculations?
The average kinetic energy of a gas molecule is
proportional to Kelvin temperature
What is kinetic energy? Why Kelvin temperature and not Celsius or Fahrenheit? What does proportional mean?
Gas particles are in constant motion, moving rapidly in
straight paths. *
Is this true?
What do we know about their motion?
Why would the real situation make the calculations more difficult?
Ideal Gases
An imaginary gas that perfectly fits all the assumptions of the kinetic molecular theory (KMT).
Expansion
Gases do not have definite shape or volume.
The expand to any container they are enclosed in.
A gas in a 1 L container is then put into a 2 L container. How much volume does it have now?
Fluidity
In an ideal gas, the gas particles glide past each other.
This feature allows gases to be referred to as fluids just like liquids.
Low Density
Density of a gas substance is only about 1/1000 of the same substance in liquid or solid state.
Why is this true?
Diffusion
Spontaneous (does not require energy) mixing of particles of two substances caused by their random motion
Pressure
Pressure is not the same as force.
Pressure is a force over an area.
Example: psi = Pounds per in2
Units of Pressure
kPa, atm, mm of Hg, torr
Helpful Conversions
1 atm = 760 mm Hg
1 atm = 760 torr
1 mm Hg = 1 torr
1 atm = 101.325 kPa
Standard Temperature and Pressure (STP)
Standard Temperature is 00C or 273 K
Standard Pressure is 101.3 kPa or 1 atm
Combined Gas Law
P1V1 = P2V2
T1 T2
If you remember this law, hold constant the other variables not used and you have all the gas laws we’ve used so far.
Dalton’s Law of Partial Pressure
Be sure all units of pressure are the same.
If not, convert all units to the same unit of measure
The total pressure is equal to the sum of the partial pressures
Ideal Gas LawPV=nRT
P = Pressure (atm)
V = volume (L)
n = number of moles
R = 0.0821 atm x L / moles x K
T = temperature (K)
You must use these units for the R constant to be correct.
Name the Law!
You will be given a series of laws and asked to name the law or you will be
given the name and be asked to come up with the formula!