Transcript 3.2 Gas Laws - Shore Regional High School

3.2 Gas Laws
Objectives:
oPredict changes in gas pressure due to changes in
temperature, volume and number of particles
oExplain Charles’s law, Boyle’s law, and the combined
gas law
oApply gas laws to solve problems involving gases
Pressure
• Def: the result of a force distributed over an
area
• SI unit: force/area = N /m2 = Pascal (Pa)
• Collisions with particles in a gas causes
pressure in a closed container
• Ex: squeezing a water bottle
Which seat is more comfortable?
Why?
Factors the affect gas pressure
1.
Temperature: Raising
the temperature of a gas
will increase the
pressure if the volume
and the number of
particles is kept
constant.
As the temperature
increases, what happens
to the speed of the
particles?
Therefore what happens
to the KE?
Temperature, cont’
This causes the particles to
collide more often with
the walls of the container
therefore increasing
pressure.
Ex: The air pressure on
the fire truck is 125 psi
(pounds per square inch).
After a long drive, will the
tire pressure increase,
decrease or remain the
same?
2. Volume
• As volume decreases,
the pressure will
increase if the
temperature and the
number of particles
are constant.
• Ex: breathing
3. Number of particles
• An increase in the number of particles will
increase the pressure if the temperature and
volume are constant.
• More particles means more collisions
Charles’s Law
• Jacque Charles was a
French physicist
• 1746-1823
• He investigated the behavior of
gases
• When he graphed data on
temperature and volume he
found that he always got a
straight line.
• His law states that volume of a
gas is directly proportional to
its temperature in Kelvin's if
pressure and the number of
particles are kept constant.
Boyle’s Law
• Robert Boyle
• 1622
• His law states that the
volume of a gas is
inversely proportional
to its pressure if the
temperature and the
number of particle
same constant.
The Combined Gas Law
• Temperature and volume are not always
constant, so it is important to be able to
determine the affects they will have.
• Ex: sending a weather
balloon into the
atmosphere
(depending on the air
pressure and
temperature the
balloon may expand or
compress and pop)
Math Skills
• A cylinder that contains air at a pressure of
100 kPa has a volume of 0.75 L. The
pressure is increased to 300 kPa. The
temperature does not change. Find the new
volume of air.
Review
• How does pressure change with increasing
temperature?
• How does pressure changed with decreasing
volume?
• How does the number of particles affect pressure?
• Why is knowing the relationship between volume,
temperature and pressure important?