A: 7 March 2012 Take Out Homework: Week 24 p. 3-4 Objective: You will be able to: describe gas...
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Transcript of A: 7 March 2012 Take Out Homework: Week 24 p. 3-4 Objective: You will be able to: describe gas...
A: 7 March 2012
Take Out Homework: Week 24 p. 3-4
Objective: You will be able to: describe gas behavior, five
assumptions we make about gases and how they relate to pressure exerted by a gas on their container.
Do now: Brainstorm: Write down everything you know about gases!
Agenda
I. Do nowII. Go over homework answersIII. Percent yield exit ticketIV. Properties of a gas notesV. Be a gas!! Collect and analyze dataHomework: Unit 6 packet page 2:
Thurs.Metacog. worksheet part 2: Thurs.
When you finish the exit ticket
Flip it over Work silently on Week 24 p. 4: due
Weds. if you haven’t already finished it.
A: 8 March 2012
Take Out Homework: Packet p. 2 and Metacog. worksheet
Objective: You will be able to: describe and model gas behavior and how
gases exert pressure their container. Do now: What’s one class where you “fell
off” (or almost did!) recently? At what point in the gradual release model
did you “fall off?” What strategy did you use to “get back on?”
Agenda
I. Do nowII. Gas behavior discussionIII. Be a gas!! Collect and analyze dataHomework: Finish Unit 6 packet
pages 4-5: Fri.Quiz on 5.9
Exit Ticket
Quiz on 5.9 tomorrow!
Properties of Gases
Kinetic Theory
Kinetic Theory: Gas particles are always in constant motion.
Assumptions of Kinetic Theory
1. Gases are composed of separate, tiny particles called molecules
2. Gas molecules are in constant, rapid, straight line motion (which means that gas molecules have kinetic energy)
3. The collisions between molecules are completely elastic (when molecules collide, there is no exchange of energy)
4. The molecules of a gas have no attraction or repulsion for each other
5. Each molecule in a gas has a different velocity
Gases are…
Compressible: There is so much space between gas particles that a sample of gas can be squished into a smaller space!
Gases are…
Expandable: They always take up their entire container!
Modeling Gas Behavior
Unit 6 p. 3 You’re going to be a gas! How will you behave?
When you make a collision with the inside of the flask or a fellow gas particle, say “Ping!” Don’t make any other noise!
Listen CAREFULLY for directions!
Expectations
Listen carefully to directions and follow them closely.
Obey the assumptions of a gas – travel in straight lines, collide elastically, etc.
When you collide, do so gently and responsibly.
Say “Ping!” only when colliding. Have fun and make this work for us!
Graph
1: Temperature vs. “Pings” 2: Flask size vs. “Pings”
Title, axis labels, units, axis scale, plot points, line of best fit
Complete page 5 Then, individually, complete pages
6-7
Homework
Finish Unit 6 packet pages 4-5: Fri. 5.9 Quiz tomorrow
When you were a gas…
You noticed that: As heat increased, particles moved
faster so pressure increased. As the number of moles increased,
there were more collisions, so pressure increased.
As volume decreased, there were more collisions, so pressure increased.
A: 9 March 2012
Take Out Homework: Packet p. 4-5 Objective: You will be able to:
convert between units for temperature, pressure, volume, moles and mass
describe gas behavior and the relationship between pressure and volume.
Do now: Describe gas behavior in 1-2 complete sentences.
Agenda
I. Do nowII. Quiz on 5.9III. Graph analysisIV. Units for gas calculationsV. My life as a gas moleculeVI. Pressure vs. volume labHomework: Finish Unit 6 packet
pages p. 6-14: Tues.
Variables that Affect a Gas
1. Temperature• How much kinetic energy does the gas
have?2. Pressure
• How much force is squeezing on the gas?
3. Volume• How much space does the gas take up?
4. number of Moles• How many atoms or molecules of gas
are there?
Temperature
Temperature needs to be in Kelvin K = oC + 273 oC = K – 273
Example: Convert 100oC to Kelvin. 100oC + 273 = 373 K
Example: Convert 393 K to oC. 393 K – 273 = 120oC
Temperature
What if temperature is in oF?
What is 80oF in oC? What is 15oC in oF?
325
9
)32(9
5
CF
FC
Units of Pressure
P = Pressure P must be in atmospheres (atm)
1 atm is the mass of our atmosphere pushing downon you!1 atm = 760 mmHg1 atm = 101.3 kPa1 atm = 14.7 psi
1 atm
Volume
Volume must be in Liters 1000 mL = 1 L
Ex: How many liters are equal to 450 mL?
Ex: How many milliliters are equal to 2.5 L?
Unit Conversions
pages 8-11
My life as a gas molecule
p. 6-7 Write silently – 15 minutes Then, sketch your picture.
I’ll bring around some colored pencils.
or begin working on the homework on p. 10-11
Think about sharing your work!
Pressure vs. Volume Experiment
p. 12-14 – Complete with your partner
Then, work on the homework: p. 8-14
Homework
Unit 6 packet pages p. 6-14: Tues.
C: 9 March 2012
Take Out Homework: Packet p. 6-7 Objective: You will be able to:
show what you know about percent yield and gas units and pressure
develop criteria for graphing data Do now: How many kPa are equal to
850 mmHg?
Agenda
I. Do nowII. Quiz on 5.9III. Reading?IV. Graph criteriaV. Exit tickets on 6.1 and 6.2Homework: Be sure your packet is
complete through page 14!
Graph Criteria
0 5 10 15 20 250
0.5
1
1.5
2
2.5
Volume vs. Pressure of a Gas in a Syringe
Volume (mL)
Pre
ssu
re (
atm
)
In your notebook:
Brainstorm: What are the criteria for an excellent graph?
For example: Title
With your group
Compile a complete list of all the criteria
Criteria for an Excellent Graph
A
B
C
D
E
F
G
H
I
J
Rate Your Graph
What criteria did you meet? (Green) What criteria did you fail to meet so
far? (Orange)
Edit your graph so it meets all the criteria.
Complete the analysis questions. Due Monday!
A: 13 March 2012
Take Out Homework: Packet p. 12-14 Objective: You will be able to:
demonstrate your current knowledge of unit conversions and gas behavior
model strategies for effective effort Do now: Calculate: How many kPa are
equal to 850 mmHg?
Agenda
I. Do nowII. Graph interpretation: page 12-14III. Exit tickets on 6.1 and 6.2IV. Clean out folder/notebookV. Effective EffortHomework: Folder check: Weds.Metacog. Worksheet part 3: Weds.
Hand in your packet
p. 12-14 graded
Exit Ticket 6.1 and 6.2
When you finish, begin to organize your notebook and folder.1. Keep in your folder: Unit 6 stuff and
metacognition stuff.2. Your notebook should have NO papers
stuck in it (a periodic table is ok)3. Paperclip Unit 5 stuff together, but
keep at your desk.4. 5 HW points tomorrow for having an
organized folder and notebook!
C: 14 March 2012
Take Out Homework: Open your folder
Objective: You will be able to: relate temperature and volume of
a gas use the gas laws equations to
relate temperature, pressure and volume
Do now: From memory, list two of the things we assume are true about gases. Then check your notes for the answers!
Agenda
I. Do nowII. Track Exit Ticket 6.1 and 6.2III. Gas Laws CalculationsIV. Charles’ Law LabHomework: p. 16, 17, 18 #1-4: Mon. p. 23 #1-4: Mon. Quiz on 6.1 and 6.2 tomorrow.
Track Exit Ticket 6.1 and 6.2
On the front of your Unit 6 Packet! Then, correct your answers.
Solving Gas Laws Problems
How are those variables related?
2
22
1
11
T
VP
T
VP
This equation is for calculating what happens to a sample of gas if one variable is changed
If you change any one of these variables, all the others will change
If one variable is held constant (not changing) in the equation, it can be crossed out
Pressure and Volume
2
22
1
11
T
VP
T
VP
Let’s say we hold temperature constant That is, we don’t allow temperature to
change. If we increase pressure, volume will
decrease. If we decrease pressure, volume will
increase.
Pressure and Volume
At the earth’s surface, the volume of a balloon is 2.0 liters. If temperature remains constant, calculate the new volume if the balloon is submerged underwater 100 feet, where there is pressure of about 4 atmospheres.
P1V1=P2V2
pressure on earth’s surface = 1 atm
1 atm∙2.0L=4 atm ∙V2
2 = 4 V2
divide both sides by 4 V2 = 0.5 L
The volume will decrease to 0.5 L!
2
22
1
11
T
VP
T
VP
Volume and Temperature
2
22
1
11
T
VP
T
VP
Let’s say we hold pressure constant That is, we don’t allow pressure to
change. If we increase volume, temperature
will also increase. If we decrease volume, temperature
will also decrease.
Volume and Temperature
A balloon, at room temperature (20oC), has a volume of 2.0 L. The balloon is gently heated until the gas inside it is 80oC. If pressure stays constant, calculate the new volume of the balloon.
20oC + 273 = 293 K
80oC + 273 = 353 K
multiply both sides by 353.
2
22
1
11
T
VP
T
VP
2
2
1
1
T
V
T
V
K
V
K
L
353293
0.2 2
K
V
3530068.0 2
LV 4.22
Pressure and Temperature
2
22
1
11
T
VP
T
VP
Let’s say we hold volume constant That is, we don’t allow volume to
change. If we increase pressure, temperature
will also increase. If we decrease pressure, temperature
will also decrease.
Pressure and Temperature
A can of hairspray has an internal pressure 2 atmospheres at room temperature (20oC). If the can is placed near the heater and the temperature increases to 50oC, what is the new pressure inside the can, if the volume of the can stays constant?
20oC + 273 = 293 K
50oC + 273 = 323 K
multiply both sides by 323.
2
22
1
11
T
VP
T
VP
2
2
1
1
T
P
T
P
K
P
K
atm
323293
0.2 2
K
P
3230068.0 2
atmP 2.22
Charles’ Law Lab p. 15
It’s not cold outside. (Yay!) But we need a cold place to do this
lab… Faculty room freezer! We’ll work on the procedure as a
class, then you’ll work with your group to complete the graph, analysis and conclusions.
Due tomorrow!
C: Homework due Mon. 3/19
p. 16, 17, 18 #1-4 p. 23 #1-4
Quiz tomorrow on 6.1 and 6.2
A: Homework due Fri. 3/16
p. 16, 17, 18 #1-4 p. 23 #1-4
Practice Problems
1. P1 = 1.0 atm P2 = 3.0 atm
V1 = 200 mL V2 =
2. V1 = 4 L V2 = 1 L
T1 = 30oC T2 = ?
3. P1 = 800 mmHg P2 = ?
T1 = 0oC T2 = −25oC
Word Problems
1. A helium balloon at 1.0 atmosphere at 25oC has a volume of 2.0 liters. If the balloon is brought up into the air where the pressure is 0.80 atmospheres, calculate the new volume, assuming that the temperature remains constant.
2. A can of hairspray has an internal pressure of 3.00 atm at 25oC. Calculate the new internal pressure if the temperature of the can is rasied to 100oC.
Homework
p. 15-19, 22-24: Thurs.
C: 15 March 2012
Objective: You will be able to: solve gas laws problems manipulate and make observations about a
sample of gas Do now: You have two balloons of the same
volume. You leave one on your desk, but tie the other one to the wing of an airplane that then flies 14,000 feet into the atmosphere. Which balloon has the greater volume assuming the temperatures are the same? Why?
Agenda
I. Do nowII. Quiz on 6.1 and 6.2III. Using the gas laws equations
examplesIV. Practice ProblemsV. Gases computer simulationHomework: p. 16, 17, 18#1-4: Mon.p. 22, p. 23 #5-6, p. 24 #7-8, p. 30-
34 all: Mon
A: 15 March 2012
Objective: You will be able to: solve gas laws problems using the
combined gas law and the ideal gas law. Do now: You have two balloons of the
same size. You leave one on your desk, but tie the other one to the wing of an airplane that then flies 14,000 feet into the atmosphere. Which balloon has the greater volume assuming the temperatures are the same? Why?
Agenda
I. Do nowII. Quiz on 6.1 and 6.2III. Using the gas laws equations
examplesIV. Practice ProblemsHomework: p. 16, 17, 18#1-4: Fri..p. 22, p. 23 #5-6, p. 24 #7-8, p. 30-
34 all: Fri.
Quiz
When you finish, turn it in. Then, complete p. 23 #1-6
Combined Gas Laws
With your partner, complete p. 25-26
A: 16 March 2012 Take Out: p. 25 Objective: You will be able to:
solve gas laws problems using the ideal gas law.
manipulate V, T, P and n, and make observations and calculations.
Do now: A 0.50 liter can of hairspray is at room temperature (20oC) and standard pressure. If I place the can in the oven (200oC), what will the pressure inside the can be?
If the can of hairspray can withstand an internal pressure of 1140 mmHg, will the can explode?
Agenda
I. Do nowII. Using the ideal gas law equation:
examplesIII. Practice ProblemsIV. Gas laws computer simulationHomework: p. 28-29, 31-32: Tues.
P, V and T
can be related in a slightly different equation along with number of moles
Can be used if the conditions aren’t changing (that is, P, V, and T are staying the same)
How are P, V, T and number of moles (n) related?
Ideal Gas Law: PV=nRT P = Pressure V = Volume n = number of moles R = constant T = Temperature
What do you need to know about PV=nRT?
R is the gas constant
It is the same for every gas in every problem!
Kmol
atmL
0821.0
Standard Temperature and Pressure (STP)
Standard Temperature: OoC =273 K
Standard Pressure: 1 atm
Problems often state “standard temperature and pressure” or “at STP”
Example problems
using the combined gas law
PV=nRT
What is the volume of 2.0 moles of gas at standard temperature and pressure?
nRTPV K
Kmol
atmLmolVatm 2730821.00.21
LV 8.44
PV=nRT
At what temperature will 1.0 mole of gas at 2 atmospheres occupy a volume of 20 liters?
nRTPV T
Kmol
atmLmolLatm
0821.00.1202
T 0821.040
KT 487
CK o214273487
Practice Problems
p. 24, 28, 29
Practice Problems
1. A container with rigid sides has a volume of 2.0 liters. It is filled with 3.0 moles of oxygen gas at 25oC. Calculate the pressure inside the container in atm and in mmHg.
2. A balloon at 70oC is filled with helium gas. The volume of the balloon is 5.0 liters at 1.00 atmosphere. How many moles of helium must be in the balloon? How many grams of helium is this?
Computer Simulation
p. 20-21 First, make some changes… Work with your partner; share one
laptop. Log on to the website, and follow the
directions. Record your observations carefully and
completely! Then, do the practice problems. Due at the end of the period!
C: Homework: due Monday
p. 16, 17, 18#1-4: Mon.p. 22, p. 23 #5-6, p. 24 #7-8, p.
30-34 all: Mon
Need extra help? I’ll be here until 4:00 on Friday in Room 203!
A: Homework: due Fri.
p. 16, 17, 18#1-4: Fri.p. 22, p. 23 #5-6, p. 24 #7-8, p.
30-34 all: Fri.
Need extra help? I’ll be here until 4:00 on Friday in Room 203!
A: 20 March 2012
Take Out Homework: Turn to p. 31 Objective: You will be able to:
experimentally determine R (the gas constant)!
Do now: Calculate the number of moles of oxygen gas required to fill a 2.0 liter flask at STP.
How many molecules of oxygen is this?
Agenda
I. Do nowII. Go over homework p. 30-34III. Exit ticket on 6.3 and 6.4IV. Determining R experimentallyV. Hand in packet (p. 12-21 = three
lab grades!)Homework: Quiz on 6.3 and 6.4
Friday
Exit Ticket
When you finish, turn it in. Then, read p. 36 of the Unit 6
packet.
Determining R Lab
If you can measure P, V, n and T… You can calculate R!!
Our gas…
A butane lighter (formula?) This lab doesn’t involve a flame. Please don’t waste your butane by
“flicking the Bic” until it’s under water
Demonstration
steps 5-9 watch carefully! Dry the lighter before re-weighing.
During the lab
Stay at your station. Work carefully and efficiently. Read each step twice, and follow it
exactly!! Record your data as you collect it.
Before you go
Leave your packet on the kidney table!
Homework: 6.3 and 6.4 Quiz Friday