Unit 5: Gases – More Gas Laws:
Charles’s Law and Boyle’s Law
11.13 & 14 Ms. Boon Chemistry
Objectives:
•I can define Standard
temperature and pressure.
•I can state Charles’s Law &
Boyle’s Law and use them to
solve gas law problems.
Agenda
•
•
•
•
•
Catalyst
• Standard temperature
and pressure is 273K
and 1 atm.
• Is standard
temperature cold or
hot? Explain?
• Where could you go to
be at standard air
pressure?
Catalyst
Balloon & Bottle
Charles’s Law
Boyle’s Law
HW: Complete mixed practice
Exit Slip
problems on worksheet.
Homework Review Pp. 445 #3, 9, 10, 24, 25
• 3. The fluidity of a gas is due to the fact that gas particles are
widely separated and moving at high speeds. They move past
each other easily.
• The wide separation of gas particles also explains a gas’s
compressibility. Because the particles are far apart, gases can
be compressed or squished to fill a smaller volume.
• The constant rapid, random motion of gas particles and the
resulting collisions with each other and the walls of their
container is what cause the pressure exerted by a gas.
Homework Review Pp. 445 #3, 9, 10, 24, 25
• 9. Two characteristics of an ideal gas are that it perfectly
obeys the ideal gas law and conforms to the kinetic
molecular theory.
• 10. Diffusion is the process by which gas particles move
from an area of high concentration to low concentration.
The gas particles spread out until they are equally spread
out.
Homework Review Pp. 445 #3, 9, 10, 24, 25
• 24. A gas’s pressure is directly proportional to
temperature when volume is held constant. This is GayLussac’s law.
•
• 25. Gay-Lussac’s law can be explained using Kinetic
Molecular Theory. Gas particles at higher temperature
will have a higher average kinetic energy, which means
that at constant volume they will collide with each other
and with the walls of their container more often. This
means that the particles exert more pressure because
pressure is a measure of the force exerted per unit area.
Balloon & Bottle
• The demonstration shows the relationship
between ___________ and ____________.
• As temperature increases, volume
___________________. As temperature
decreases, volume ___________.
Balloon & Bottle
• Summary of Procedure: (1) A small amount of water
(~15 mL) is poured into an empty Erlenmeyer flask. (2)
The flask is heated until steam comes out and the water
boils for about 30 seconds. (3) Then the flask is removed
from the heat and a balloon is attached over the mouth
of the flask.
Hypothesis: What do you
think will happen to the
balloon? Why?
Balloon & Bottle: Explanation
• Describe what happened using the kinetic
molecular theory of gases!
•When we put the flask on the hot
plate, the temperature of the gas
inside the flask increases. The fast
moving gas particles take up a large
amount of volume.
•When we put the balloon on the
bottle, we fix the number of gas
molecules in the bottle and balloon.
•The gas temperature begins to
decrease because we took the flask
off the heat.
•This causes a decrease in volume.
Charles’s Law: Temperature
and Volume Relationships
• Around 180o, Jacques Charles discovered that gas
volume and absolute temperature are directly
proportional at constant pressure.
•For example, if the absolute
temperature (temperature expressed in
Kelvin) is doubled, the volume is
doubled. If the volume is cut in half,
the absolute temperature is also cut in
half.
• When gas pressure is held constant, the
following equation expresses the volume and
temperature relationship:
If any three of the variables in
the above equation are known,
then the unknown fourth
variable can be calculated.
• Example 1: V1 = 100 L, T1 = 100 K,
V2 = ??, T2 = 200 K
• Example 2: At 273K, the volume of
a sample of nitrogen is 30 L.
What will the temperature be if
the volume increases to 300 L?
• Example 3: At 500K, a 1000 mL
sample is at standard pressure. If
the pressure is held constant and
the temperature decreases to 5K,
what is the new volume in mL?
Boyle’s Law: Pressure and
Volume Relationships
• In 1662, English scientist Robert Boyle discovered that
gas volume and pressure are inversely proportional
at constant temperature.
•For example, if the pressure is
doubled, the volume is cut in half. If
the volume is cut in half, the pressure is
doubled.
• When gas temperature is held constant, the
following equation expresses the volume and
pressure relationship:
If any three of the variables in
the above equation are known,
then the unknown fourth
variable can be calculated.
https://www.youtube.com/watch?v=Dc
nuQoEy6wA
• Example 1: V1 = 100 L, P1 = 100
atm, V2 = ??, P2 = 20 atm
• Example 2: A sample of gas occupies 523 mL at
1.00 atm. The pressure is increased to 1.97 atm,
while the temperature remains the same. What
is the new volume?
• Example 3: A sample of gas occupies 100 L at
2.00 atm. The pressure is decreased to 760 mm
Hg. What is the new volume?
• Standard Temperature and Pressure:
If you see STP (standard temperature and pressure)
you should immediately think:
0° C (or 273K) and 1 atm (or 760 torr or 760 mm Hg)
Example: A balloon filled with helium
has a volume of 22.4 L at standard
temperature and pressure. If the
temperature is held constant, what
will the volume be at 2.0 atm?
Exit Slip 4c 11.13 & 14
1.
At constant pressure, as temperature increases, volume
__________. Volume and temperature are _________
proportional.
2.
At constant temperature, as pressure increases, volume
__________. Volume and pressure are _________
proportional.
3.
A sample of nitrogen has a volume of 275 mL at 273 K. The
sample is heated and the volume becomes 550 mL. What is the
new temperature in Kelvins?
4.
A sample of gas occupies 1.55 L at 27.0° C and 1.00 atm
pressure. What will the volume be if the pressure is increased
to 50.0 atm, but the temperature is kept constant?