### Gas Laws

```GAS LAWS
2014
http://www.nclark.net/GasLaws
GAS LAWS
Charles’ Law (slide 4)
 Boyle’s Law (slide 31)
 Guy Lusaac’s Law (slide 77)
 LeChatelier’s Principle (slide 105)
 Ideal Gas Law (slide )

PRESSURE CONVERSIONS
STP means standard temperature and pressure
1 standard atmosphere = 1.000 atm =
760.0 mm Hg = 760.0 torr =101,325 Pa =
14.69 psi
***all of these equal each other!***
Temperature: 0 ˚C or 273 K
CHARLES
LAW
CHARLES’S
LAW

*Constant amount of gas at a
constant pressure
Volume of a gas increases
with temperature.
(Gases expand with heat).
↑T=↑V
Jacques Charles proposes Charles's Law.
1787
↓T=↓V

The formula for the law is:
V1/T1 = V2/T2
Where:
V1 is the initial volume
T1 is the initial temperature
V2 is the final volume
T2 is the final temperature
***temperature MUST be in Kelvin
(absolute zero) NOT oC or oF!***

Set up of Demonstration.
 Blow
up two similar balloons so they have the same
circumference.
 Place balloon in ice water on one side to 500 ml.
 Place equal balloon in hot water on one side to
500ml.
 Put small block and weight, or use finger to depress
balloon under water.
 Sketch/Record difference in volume between the
balloons.
 How does temperature effect the volume of a gas?
Think about the gas molecules in each balloon.
DEMONSTRATION
-
Balloon in hot and
cold
water
--What happens??
- Glass bottle with balloon
in hot water

Demonstration: Fit a balloon to the top of a
glass bottle and place in pan with water.
 Place
on top of heat source and observe.

Demonstration: Fit a balloon to the top of a
glass bottle and place in pan with water.
 Place
on top of heat source and observe.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.

This law means that when the temperature
goes up, the volume of the gas goes up.
When the temperature goes
down, the volume of the gas
decreases
.
http://group.chem.iastate.edu/Greenbowe/s
ections/projectfolder/flashfiles/gaslaw/charl
es_law.html
Station 2 Microwave Popcorn


Key Concept ~ When the temperature of a gas is
increased, its volume will increase.
Students will be micro waving small amounts of popcorn
in a clear bowl. Popcorn pops when the moisture inside
boils and expands, bursting the kernel open. Instructions:
Place about two tablespoons of popcorn in the clear
plastic bowl. Put the top on the bowl and place in the
microwave. Close the microwave door and turn the
microwave on high. Watch as closely as you can as the
popcorn kernels begin to pop, but of course DO NOT OPEN
THE DOOR! As soon as the vigorous popping stops, turn off
the microwave. Questions: Describe what you see (yeah, I
know, but try). What do you think makes the popcorn pop?
Put your popcorn in a paper bag and then squirt in some
butter if you wish.

Station 9 Super Duster & Office Buster

Key Concept ~ When the volume of a gas increases, its temperature
will decrease.

Obtain a can of compressed "air," such as those used to clean
electronic equipment. As you depress the nozzle, the gas inside
(typically an HFC) responds to the reduced pressure by "boiling" or
rapidly turning into a gas. This is an endothermic process so the can
gets extremely cold (can even cause frost-bite if you hold it too long.)
I like the students to relate this to the phenomenon of water boiling
at lower temperatures at high altitudes due to the lower pressure.
(Lots of campers know this very well.) The classic Drinking Bird uses
a similar concept and makes a good companion to this station.
Simply challenge the students to explain the bird's motion.
Instructions: Wrap your hand around one of the duster cans. Make
sure your palm is in complete contact with the can. Now, depress the
nozzle. Questions: What do you feel? Why? Shake the can. What do
you notice? Try to explain what happens when you depress the
nozzle - See more at: http://www.arborsci.com/cool/chemistry-gaslaws-smorgasborg#sthash.Qy9PndDT.dpuf
Other Examples Of Charles’ Law

When temperatures get colder, you may need
to add some more molecules to get the safe

You may notice that your sports equipment
doesn’t work well when you go out into your
garage in the winter.
 The air molecules are moving very slowly so
the ball is flat.

You may notice that your sports equipment
doesn’t work well when you go out into your
garage in the winter.
 The air molecules are moving very slowly so
the ball is flat.
A 2.0L sample of air is collected at 298 K and then cooled to 278 K. The
pressure is held constant at 1.0 atm.
a. Does the volume increase or decrease?
b. Calculate the volume of air at 278 K.
Step One: Write down the information given V1 = 2.0L
V2= ?
and check units.
T1 = 298 KchangeT2 = 278 K
sameP = 1.0 atm
P1 = 1.0 atm
2
Step Two: Write down the correct formula.
V1/T1 = V2/T2
Step Three: Plug the given information into the formula and solve for the
unknown variable.
V1/T1 = V2/T2
2.0 =
298
278
V2
(2.0)(278) = V2 (298)
298
298
Step Four: Record the two answers. a. The volume will decrease
b. V2 = 1.9L
BOYLES
LAW
BOYLE’S LAW:
↓ volume = ↑ pressure
↑ volume = ↓ pressure
1662, Robert Boyle
Pressure and Volume are
inversely proportional.
Very Important! Record in
Journal.

Activity! Syringes

Activity! Syringes
 Depress
plunger on the syringe.

Activity! Syringes
 Depress
plunger on the syringe.
 Cover hole with finger.

Activity! Syringes
 Depress
plunger on the syringe.
 Cover hole with finger.
 Try and pull handle (gently please).
 Why
is it difficult?
Keep thumb on opening.

Activity! Syringes
 Depress
plunger on the syringe.
 Cover hole with finger.
 Try and pull handle (gently please).
 Why
is it difficult?
Keep thumb on opening.

Activity! Syringes
It was difficult because your finger
created a sealed vacuum and prevented air from
entering the chamber.
Keep thumb on opening.

Activity! Syringes
It was difficult because your finger
created a sealed vacuum and prevented air from
entering the chamber. Atmospheric pressure is
1 kilogram per square centimeter at sea level.
Keep thumb on opening.

Activity! Syringes (Opposite)

Activity! Syringes (Opposite)
 Fill
syringe.

Activity! Syringes (Opposite)
 Fill
syringe.
 Cover hole with finger.

Activity! Syringes (Opposite)
 Fill
syringe.
 Cover hole with finger.
 Try and push handle (gently please).

Activity! Syringes (Opposite)
 Fill
syringe.
 Cover hole with finger.
 Try and push handle (gently please).
 How
does this represent Boyles Law?
Activity! Syringes (Opposite)
 How does this represent Boyles Law?

Activity! Syringes (Opposite)
 How does this represent Boyles Law?
 Answer: As you depress the plunger, you
increase pressure and the volume of the gas
is decreased.

Activity! Syringes (Opposite)
 How does this represent Boyles Law?
 Answer: As you depress the plunger, you
increase pressure and the volume of the gas
is decreased.
 Please determine how many milliliters you
were able to compress the gas inside using
the numbers on the syringe.

Activity! Syringes (Opposite)
 How does this represent Boyles Law?
 Answer: As you depress the plunger, you
increase pressure and the volume of the gas
is decreased.
 Please determine how many milliliters you
were able to compress the gas inside using
the numbers on the syringe.
 Answer: You should be able to compress the
gas to about 50% of it’s starting volume by
hand and then it gets difficult.

Can’t wait to
eat my
yogurt.”
“

As you inhale, your diaphragm flattens out
allowing your chest to expand and allows
more air to flow into your lungs.

As you inhale, your diaphragm flattens out
allowing your chest to expand and allows
more air to flow into your lungs.
 Air
pressure decrease, air then rushes into your
lungs.

As you exhale, your diaphragm relaxes to a
normal state. Space in chest decreases.

As you exhale, your diaphragm relaxes to a
normal state. Space in chest decreases.
 Air
pressure increases, air then rushes out of

Which is a inhale, and which is a exhale?
A
B

Which is a inhale, and which is a exhale?

A
B
Which is a inhale, and which is a exhale?
 Inhale

A
B
Which is a inhale, and which is a exhale?
 Inhale

A
B
Which is a inhale, and which is a exhale?
 Inhale
Exhale

A
B

Which is a inhale, and which is a exhale?
A
A
B
B

Which is a inhale, and which is a exhale?
A
A
B
B
Which is a inhale, and which is a exhale?
 Inhale

A
A
B
B
Which is a inhale, and which is a exhale?
 Inhale

A
A
B
B
Which is a inhale, and which is a exhale?
 Inhale
Exhale

A
A
B
B

Cartesian Diver to Display Boyle's Law
 One 2-liter bottle (clear)
 One small glass dropper
 Water

Once you've managed to gather these supplies, it would be advised to find a
handyman or somebody skilled in construction/engineering to assist in deciphering
the following steps:
 Fill the 2 liter bottle between 2/3 and 3/4 full of water.
 Take your eyedropper, the "diver" and fill it with just enough water so that the top
of the dropper is just buoyant enough to tread the water.
 Apply the lid to the 2 liter bottle. It must be airtight!
 Squeeze the bottle.
 Observe.

If you have successfully followed the instructions, good for you. Your Cartesian diver
should dive to the bottom as you squeeze the bottle. That's Boyle's law in action!
When you squeeze inward, you are reducing the volume of the bottle. As we know,
this reduction in volume increases the pressure of all of the gas, including what is
This increase in pressure pushes against the water, forcing more water up into the
eyedropper. As you can see, this additional water decreases the diver's buoyancy,
causing it to "dive" to the bottom. Stop squeezing the bottle and everything returns to
normal, allowing your diver to ascend back to the water's surface. You would be keen
to let go slowly, so your diver doesn't ascend too quickly. Wouldn't want it getting the
bends!



The Bends (Decompression Sickness) –
Bubbles form in blood if you rise to quickly
because of the rapid decrease in pressure.

The Bends (Decompression Sickness) –
Bubbles form in blood if you rise to quickly
because of the rapid decrease in pressure.

A diver must save time to travel to surface
BOYLE’S LAW
Inverse ↑ P : ↓ V
Formula:
P1V1 = P2V2
This works because, if the volume of
* a constant amount of gas a container is increased, there is a
greater area in which the particles of
gas inside the container can move.
* constant temperature
Since the particles have more space,
there is less force exerted on the
walls of the container by the
particles and therefore, less
pressure.
What pressure is required to compress 196.0
liters of air at 1.00 atmosphere into a cylinder
whose volume is 26.0 liters?
Step One: Write down the information given and check units.
P1 = 1 atm
V1 = 196 L,
P2 = ?
V2 = 26 L
Step Two: Write down the correct formula.
P1V1 = P2V2
Step Three: Plug the given information into the formula and solve
for the unknown variable.
(1 atm) (196 L) = (P2) (26 L)
P2 = 7.5 atm
Freon-12 was a widely used refrigerant but has been replaced by other refrigerants
that do not lead to the breakdown of the ozone layer. Consider a 1.5 L sample of
Freon-12 gas at a pressure of 56 torr. If the pressure is changed to 150 torr at a
constant temperature….
a. Will the volume of gas increase or decrease?
b. What will be the new volume of the gas?
Step One: Write down the information given and check units.
V1 = 1.5 L
P1 = 56 torr
V2= ?
P2 = 150 torr
Step Two: Write down the correct formula.
P1V1 = P2V2
Step Three: Plug the given information into the formula and solve for the unknown
variable.
P V =P V
1 1
2 2
(56)(1.5) = (150)(V2)
150
150
Step Four: Record the two answers.
a. The volume of gas will
decrease
b. V = 0.56 L
GUYLUSAAC’S
LAW
GUY LUSAAC’S LAW
French chemist Joseph Louis Guy-Lussac
in 1802
= the pressure of a fixed mass
and fixed volume of a gas is
directly proportional to the gas's
temperature
↑ temperature = ↑ pressure
↓ temperature = ↓ pressure
P/T=k
Where: P is the pressure of the gas
T is the temperature of the gas (in kelvins)
k is a constant
When comparing
two substances:
P1/T1=P2/T2
As pressure increases, temperature increases.
As pressure increases, temperature increases.
As pressure decreases, temperature decreases.
+
+

This photoshop job might look “Funny”.

Caution! Graphic Images of burns / the
dangers of pressure and temperature.

The consequences of severe burns and
explosions are not “funny”.
BOILING WATER AT ROOM TEMPERATURE
↑ pressure =
↑ temperature
Describe what should
happen?
What does happen?
EXAMPLE:
Five grams of octane (C8H18) and enough oxygen to
burn it are in an automobile cylinder compressed to
20 atm at 28°C. The mixture explodes and heats the
cylinder to 150°C. What is the pressure in the (same
sized) cylinder after the explosion?
P1 = 20 atm
T1 = 301K,
P1 / T1 = P2 / T2
P2 = ?
T2 = 423 K
(20)/(301) = (P2)/(423)
P2 = 28.4 atm
EXAMPLE 2
A 20 L cylinder containing 6 atm of gas at 27 °C.
What would the pressure of the gas be if the gas
was heated to 77 °C?
P1 =
T1 =
P2 =
T2 =
P1 / T1 = P2 / T2
EXAMPLE 2
A 20 L cylinder containing 6 atm of gas at 27 °C.
What would the pressure of the gas be if the gas
was heated to 77 °C?
P1 = 6 atm
T1 = 27 +273 = 300K
P2 = ??
T2 = 77+273 = 350K
P1 / T1 = P2 / T2
EXAMPLE 2
A 20 L cylinder containing 6 atm of gas at 27 °C.
What would the pressure of the gas be if the gas
was heated to 77 °C?
P1 = 6 atm
T1 = 27 +273 = 300K
P2 = ??
T2 = 77+273 = 350K
P1 / T1 = P2 / T2
(6 atm) x (350K) = (P2)
(300K)
P2 = 7atm
PRESSURE CONVERSIONS
STP means standard temperature and pressure
1 standard atmosphere = 1.000 atm =
760.0 mm Hg = 760.0 torr =101,325 Pa =
14.69 psi
***all of these equal each other!***
Temperature: 0 ˚C or 273 K
LE CHATELIER’S
PRINCIPLE
If a stress is applied to a system
at equilibrium, the position of the
equilibrium will shift to reduce the
stress.
3 TYPES OF STRESS:
1.
2.
Change amount of reactants and/or products
Change Pressure
1.
2.
3.
3.
Only affects gases
b/c partial pressures ( and concentrations)
change, a new equilibrium must be reached
System will move in direction that has least moles
of gas
Change in Temperature
```