Full Lesson Plan - School of Arts & Sciences

Bill Wagenborg
Chemistry Lesson Plan
March 2007
Lesson Title: Understanding Charles’ Law
Grade Level: 8
Time Frame: 1-2 (45 Minute) Classes
Goals/Objectives: The Students Will Be Able To:
- follow a sequenced plan of instructions
- describe changes to gases caused by the addition and
absence of heat(rise and fall in temperature)
- use process skills to make inferences and predictions
using collected information
- explain the concepts involved in Charles’ Law through
discussion and written words
Pennsylvania Standards:
3.1.10 E: Describe patterns in nature, physical and man made
systems.
3.2.10 B: Apply process knowledge and organize scientific and
technological phenomena in varied ways.
Opening (Attention Grabber)
Materials: Empty Soda Can, Hot Plate, 1 Liter Beaker, Tongs, Tap Water
Teacher Action:
1.Fill up the beaker with room temperature water.
2.Place just enough water in the soda can to cover the bottom.
3.Turn the hot plate on, place the soda can on top and heat the can until the
water begins to boil. (You should see steam flowing from the top of the
can)
4.Using the tongs, grab the can at the bottom and quickly place the top
portion of it in the beaker upside down. (The sides of the can will crush
inward)
5. Allow students to hypothesize why this occurred and explain that today
they will be doing a lab that may help them understand what happened.
***Caution: Before doing this demonstration inspect the beaker for any cracks
and make sure the students are not extremely close. The force of the can crushing in a
beaker with a tiny crack can cause the beaker to break. (This happened to me before
when I was testing it before class. I reinforce the top of beaker I use with duct tape before
doing this demonstration in order to prevent any accidents)
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Materials For Lesson:
For Each Group:
2 balloons (be mindful of student allergies when choosing the type)
2 250 ml beakers
2 thermometers
2 aluminum pie pans (6-12 inches)
For The Class:
Crushed ice
Tap water
Hot Plate(s)
Pre-Class Questions:
What do you think will happen to a balloon if you heat it? Why?
What if you cool it? Why?
Draw a picture of what the gas might look like inside the balloon for each
instance.
Lesson:
Part A
The students are broken up into groups and each group will blow up a balloon in a
250 ml beaker. The balloon should fit firmly against the insides of the beaker.
They will then place the beaker in an aluminum pie shaped container. This
container will be a water bath filled with room temperature water. Using a
thermometer, the students will take and record the temperature of the water and
observe the balloon. They will make a drawing of what they think the gas looks
like inside the balloon.
The students will then place the container with the beaker in it, on a hot plate and
heat the water. (We do not have any Bunsen burners or access to gas for that
matter). They will take the temperature of the water at equal intervals (every 30
seconds for 5 minutes) and observe what happens to the balloon in the beaker
until the water begins to boil.
The students will be recording all of the information and observations in their lab
journals. They also will draw a picture of what they think the gas inside the
balloon looks like after the five minutes of heating. They will compare this to
their drawing of the gas before they added heat to the balloon and the prediction
they made in their pre-class drawing of a heated balloon.
Part B
The students will blow up another balloon inside a second 250 ml beaker and
again place it in a room temperature water bath in an aluminum pie plate. They
will record the temperature and observe the balloon’s size in the beaker. They will
make a drawing of what they think the gas looks like inside the balloon.
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Assessments:
The students will then begin to fill the water bath with crushed ice. They will
record the temperature, observe the balloon and add more ice. All will be done
over equal time intervals (30 seconds for 5 minutes).
As they did in part a, they will record all information in their lab journals. They
also will draw a picture of what they think the gas inside the balloon looks like
after the five minutes of cooling. They will compare this to the drawing they
made of the gas before they added the ice and to their pre-class drawing of a
cooled balloon.
After the lab (that day if time permits or the following class), we will have
a discussion about what the students observed and what they think may have
caused their results. They will also record their thoughts and experiences with this
lab in their lab journals. I will serve as a moderator/guide and not an answer
person. I want to see what their thoughts are and that they arrived at their
conclusions on their own.
1. The students will be given follow up questions dealing with their lab that
will be used as an assessment. The questions will be phrased in a way where
I will be able to see if they understand why the balloon increased in size in
the hot water and decreased in size for the cold. I want to make sure that
they realize that the volume of the gas inside the balloon is increasing and
decreasing.
For example:
• Were your predictions from the pre-class correct? Explain
• Based on your observations, what happens to a balloon
when heated and when cooled?
• What affect does the temperature have that causes the
balloon to act this way?
• Using this lab and what we learned about Boyle’s Law in
our previous unit as a basis, explain why the soda can got
crushed in our opening activity?(If Boyle’s Law is taught
after Charles Law you can just focus on their
explanations from the temperature and volume viewpoint
now, and readdress the pressure at a later point)
2. They will also be given a question on their unit test that takes Charles’ Law
and puts in a “real world” context.
For example:
• Why do the tires on your car appear to be deflated in the morning
after a cold night? How does this show Charles’ Law?
Or
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• You are a manager of a party store. It is a cold day and a person
just buys a bunch of balloons before leaving the store. She returns
minutes later complaining that her balloons are deflated. Using
what you have learned about Charles’ Law, give your response to
the customer.
Story of Charles Law (See Page 7): During the following class or lab wrap up session,
the students will hear the story of how Charles Law came about and how it relates to
balloons. It provides the students with a connection between a science law and a real
world application.
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Story of Charles’ Law
To begin the story of Charles law, we should first look at the early
attempts of discovery by Robert Boyle and Guilliame Amonton. In 1622
Boyle had published his work on the inverse relationship between a gas’
pressure and volume, a law that would later bear his name. He was aware of
the increase in volume of a gas when heated, but a temperature scale did not
exist then. In the early 1700’s Amonton did many experiments involving a
gas’ volume and its temperature, but like Boyle a temperature scale did not
exist. (Thall, n.d.)
So we can now look at the gentleman who the law is named after.
Jacques Charles was a Frenchman who early on in his life had very little
science education. While working in a Paris Government Office he had a
chance encounter with the American Ambassador to France, Benjamin
Franklin. After hearing of Franklin’s experiments and scientific ideas,
Charles decided to teach himself some science. This self teaching eventually
led to public lectures and then to the Academy of Science, where he began to
develop a respectable reputation. (Ellyard, 2005)
It was here in 1783 that the Montgofier brothers asked Jacques
to look at their new mode of travel, the hot air balloon. After careful
scrutiny, Charles stated that he believed that for the safest and surest form of
travel the balloon should be filled with” a very light flammable air
(hydrogen) rather than heating the air over fire.”(Ellyard, 2005) In August of
that year he but his theories to the test. He got his first balloon and filled it
with hydrogen by pouring sulfuric acid over scrap iron (later zinc). He went
to a field, where the Eiffel tower now stands, and sent his balloon up 10 km.
After more trials he soon started to notice that the balloon’s volume would
expand as the balloon went up into lower air pressure. This was not anything
new; it was simply proving Boyle’s Law from 1659. More importantly he
saw a connection between heating the gas and the gas’ volume. (Ellyard,
2005)
In 1787 Charles decided to investigate this relationship further. He
went out and got a J-shaped glass tube that Robert Boyle had used in his
study of gases. He placed the tube in a water bath so he could manipulate the
temperature of the gas. He held the pressure of the trapped gas bubble steady
by “keeping a constant difference between mercury levels in the two arms of
the tube,” (Ellyard, 2005) This would make pressure a non factor in his
experiments. He then went about changes the temperature of the water bath
and observing the effect on the trapped gas bubble. His results showed that
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the volume of the gas rose with an increase in temperature and fell with a
decrease in temperature, (Ellyard, 2005)
This relationship was dubbed Charles’ Law. This may not be fair for
two reasons. First Charles was not the first to discover this relationship.
Gulilliame Amontons had done so in 1702, but Charles’ apparatus was better
and he had more precise measurements. Secondly Charles never published
his work on the relationship between a gas’ volume and its temperature. That
distinction would go to Gay Lussac. (Ellyard, 2005)
After the French Revolution, fourteen year old Joseph Gay-Lussac
went to Paris. It was here that he received private lessons and attended
boarding school. He eventually became an assistant to French chemist
Claude Louis Berthollet who trained him in chemical research. During the
winter of 1801-1802, twenty-four year old Gay-Lussac was encouraged by
Berthollet to conduct research on the expansion properties of gases. (Green,
Peterson, 1992)
Gay-Lussac wanted to get results that were more accurate than those
obtained by Charles and others. In his experiments he “excluded water
vapors from his apparatus and made sure that the gases themselves were free
of moisture.” He concluded that “equal volumes of gases expand equally
with the same increase in temperature.”(Lussac, 1802)
There were some differences between his results and Jacques Charles.
First of all, Gay-Lussac published his results while Charles did not. Gay-
Lussac also measured the coefficient of expansion while Charles did not.
Charles only investigated oxygen, carbon dioxide, nitrogen and air.Gay-
Lussac’s results worked for all gases. Finally, because Charles had water in
his apparatus, his results showed an unequal expansion for the gases that
were water soluble. Gay-Lussac had obtained more accurate results and
published them yet the law is still more commonly referred to as Charles’
Law than Gay-Lussac’s Law. (Green, Peterson, 1992)
Like Charles before him, Gay-Lussac was an avid balloonist. In 1804
he flew to an altitude of 23,000 feet which was a record that stood for half of
a century. Eventually as, Charles predicted, hot air balloons were replaced
by hydrogen filled and later helium filled balloons. In the 1960’s hot air
ballooning became popular again as a sport. (Reese, 2004)
Charles and Gay-Lussac’s results helped other scientists discover the
absolute zero temperature of a gas. This is done by locating the theoretical
temperature in which gas has a volume of zero. (Ellyard, 2005) This is the
coldest temperature possible. It has never been achieved because gas
liquefies before reaching this temperature and is no longer subject to the gas
laws. (McGrath, 2005)
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References
Ellyard, David (2005)
Who Discovered What When.
Sydney: Reed New Holland.
Gay-Lussac, Joseph (1802)
Annales de Chimie 43, 137 (1802) [reprinted in William Francis
Magie, ed., A Source Book in Physics (New York: McGraw-Hill,
1935)]. First Section. Retrieved February 19,2007 from
http://web.lemoyne.edu/~giunta/gaygas.html
Green. Jeffery M., Peterson, Andy (1992)
Gay-Lussac-Scientist. Retrieved February 19,2007 from
http://www.woodrow.org/teachers/ci/1992/Gay-Lussac.html
McGrath, Kimberly (ed.) (2005)
World of Physics. Farmington, Michigan:
Thomas Gale Publishing. Retrieved February 19, 2007 from
http://www.bookrags.com/research/charles-law-wop/
Reese, K.M. (2004)
Gay-Lussac, Balloon Pioneer. Chemical Engineering News.
Volume 82(25) Pg 56
Thall, Edwin (n.d)
Thall’s History of Gas Laws. Retrieved February 19,2007 from
http://mooni.fccj.org/~ethall/gaslaw/gaslaw.htm
*Soda can demonstration and balloon lab based on those found in The
School District of Philadelphia’s 8 th Grade Science Textbook.
Holt Science and Technology: Introduction to Matter (2005)
Holt, Reinhart and Winston: Austin Texas.
* All photos are the property of William J. Wagenborg Jr. and may not
be used by anyone in any way.
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Pictures To Be Used For Lesson
Jacques Charles
(http://dbhs.wvusd.k12.ca.us/webdocs/GasLaw/Gas-Charles.html
Joseph Gay-Lussac
(http://dbhs.wvusd.k12.ca.us/webdocs/Gallery/Gallery6.html)
http://discover.edventures.com
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More Links
These are links to some Charles’ Law graphics.
http://www.1728.com/charles.htm
http://exploration.grc.nasa.gov/education/rocket/glussac.html
http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/c
harles_law.html
These are links to more information on hot air ballooning.
http://www.planoballoonfest.org/balloon_history.html
http://www.nationalballoonmuseum.com/exhibits.cfm?exhibitid=18
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