Gas Unit 1/5
The student will learn:
1. The five basic assumptions of the Kinetic
Molecular Theory.
2. The difference between an Ideal Gas and a
Real Gas
3. Four items necessary for gas conversions
(volume, temperature, moles, molecules)
4. Calculations of conversion between four
different pressure measurements.
atm, mmHg, mmtorr, Kpa
1.
KMT
Kinetic Molecular Theory
Gases consist of particles far apart.
2.
Collisions between particles are elastic.
elastic meaning = no net loss of KE
3.
Gas particles are in constant, rapid, random motion
4.
No forces of attraction or repulsion between gas particles.
5.
Average KE of a gas depends on Temperature of gas.
If the molecules of air that surrounds us could be
magnified until they were as big as tennis balls,
the average distance between the molecules would
be:
1.
2.
3.
4.
5.
One inch
50 feet
6 miles
1 yard
2mile
Ideal Gases: an imaginary gas that
perfectly fits all assumptions of KMT.
(Noble gases)
closest thing to it
Real Gases: does not behave completely
to the laws and theories of the KMT.
Need to know 4 items for understanding Gases
Volume: liters and milliliters
Temperature: Kelvin
convert
K
42oC =
126oC=
212oC=
Zero degrees Kelvin = absolute zero
coldest temperature
never reachable
K = 273 + oC
What is -10OC on the Kelvin scale?
1.
2.
3.
4.
5.
253K
273K
283K
+10K
None of these
Need to know 4 items for understanding Gases
Volume: Temperature:
# of moles or molecules
avogadro’s number
6.022 x 1023 molecules per mole
22.4 liters per mole
@ STP
STP === standard temperature pressure
OoC or 273K,
1atm
S.T.P. means….
1.
2.
3.
4.
-273K and 1atm
OOC and 1atm
25Oc and 760mmHg
Zero Kelvin and 760mmHg
Pressure:
atm
atmosphere of pressure
1 atm = 760 mm Hg = 760 torr = 101.3 kpa
Sea level pressure = 1 atm or 760mm Hg or 101.3 kpa
STP === standard temperature pressure
OoC or 273K, 1atm
Average pressure in Denver Colorado is 0.083atm.
Exress in mm Hg and kpa
752 mmHg to atm.
3 atm to torr
780mmHg to kPa
320 kPa to atm
799 torr to atmospheric pressure
799 torr to kPa
1.78 atm to kPa
85.4 kPa to mmHg
1.83 atm to mmHg
790mmHg to kPa
123.85 kPa to atm
745mmHg to torr
Gas Unit 1/5
The student will learn:
1. The five basic assumptions of the Kinetic
Molecular Theory.
2. The difference between an Ideal Gas and a
Real Gas
3. Four items necessary for gas conversions
(volume, temperature, moles, molecules)
4. Calculations of conversion between four
different pressure measurements.
atm, mmHg, mmtorr, Kpa
Gas Unit 2/5
The student will learn:
1. Concepts concerning Boyles Law,
Charles Law, Gay-Lussac Law.
2. Calculations of gas problems
using the Combined Gas Law.
PV = PV
T
T
Boyles Law:
keeping temperature same
P1V1 = P2V2
Pressure down = volume up
Pressure up = volume down
When cap comes off …pressure down
= volume up
Down to bottom of ocean…pressure up
= volume down
Inversely
porportioned
• Charles Law:
Pressure-Volume Inversely proportional.
Doubling the initial pressure of one liter of a gas
causes the volume of the gas to :
1.
2.
3.
4.
5.
Double
Remain the same
Decrease by 1/3
Decrease by ½
Triple
Charles Law: keeping pressure same
V1
=
T1
Versly
propoational
V2
T2
temperature up
volume up
temperature down
volume down
Balloon in freezer vs balloon next to heat
Car tires in summer vs. tires in winter
Gay-Lussac’s law : keeping volume same
Temperature up = pressure up
Temperature down = pressure down
Throw hair spray can in fire
P1 =
T1
P2
T2
Combined Gas Laws: all 3 put together
P1V1
T1
=
P2V2
T2
Worksheet 11.0
1)A scuba diver at the beach has his 24 L air tank sitting outside in a
temperature of 30 degree Celsius and the tank pressure registers at
12atm. As he dives down into the ocean the temperature of the water
and tank drop to 10 degrees Celsius. What is the new pressure of the
scuba tanks?
2.
A gas has a volume of 22 liters, a pressure of 3.5 atm and a
temperature of 278K. If I raise the temperature to 350K
and lower the pressure to 1.5 atm. What is the new
volume of the gas?
3.
A balloon has a volume of 28L at the beach with standard
pressure. As the balloon rises the volume changes to 30L and
its temperature decreased to 15Oc . The presssure is recorded
by the instrument panel to be 0.75atm at the height of its rise.
What was the temperature at the beach?
4.
If I have 15L of oxygen gas held at a pressure 55atm and a
temperature of 800K, what will the volume of the gas if I
decrease the pressure to 45atm and decrease the temperature
to 775K?
5. A student was assigned to calculate the unknown volume of
gas held at temperature of 75K in a container with a
pressure of 60 atm. If increasing the temperature to 225 K
and decreasing the pressure to 15 atm causes the volume of
the gas to be 32 liters, how many liters of unknown gas did
the student calculate?
6. An aerosol can of hair spray holds 0.25 liters of spray at STP.
Then a crazy chemistry student throws the can into a campfire,
which is 1400 degrees Celsius. How much pressure may be
generated? What will determine if the can explodes?
Ws.11.0
Gas Unit 2/5
The student will learn:
1. Concepts concerning Boyles Law,
Charles Law, Gay-Lussac Law.
2. Calculations of gas problems using
the Combined Gas Law.
PV = PV
T
T