Semester #2 Make it count!. Chem Catalyst You have two cups of water – one with COLD water and one...

Semester #2

Make it count!

Chem Catalyst

• You have two cups of water – one with COLD water and one with HOT water.

1.) What is going on with the molecules in the COLD water to make it feel cold?

2.) What is going on with the molecules in the HOT water to make it feel hot?

How can I do well in chemistry?1.) COME TO CLASS on time and prepared

2.) Complete all assignments during class time

3.) TAKE NOTES!!! Use them for open note quizzes and studying for tests.

4.) Do the test review assignment so you can retake the test if you do poorly.

5.)The DAILY stuff MATTERS

6.) Stay organized – You must have a folder only for chemistry and a notebook by Friday

Demonstration

Notes

Kinetic Molecular Theory (KMT)• The theory describing how molecules move in solids, liquids and gases

• Used to explain changes in states of matter (solid to liquid, liquid to gas, etc.)

•Hotter = faster molecules•Colder = slower molecules

Eureka Video Episode 16Answer Questions 1-3

Eureka Video Episode 17

ChemCatalyst

• How do the movement of molecules in solids differ from the movement of molecules in liquids?

Solid Liquid Gas

Flow?

Keep shape?

Compressible?

Phase changes

Solid Liquid Melting

Liquid Solid Freezing

Liquid Gas Boiling/Evaporation

Gas Liquid Condensation

Solid Gas Sublimation

Gas Solid Deposition

Eureka Video Episode 18

Chem Catalyst

• Describe in your own words what happens to molecules at the surface of a liquid to allow them to evaporate.

• Do the H2O molecules break apart into H and O when they evaporate? Why or why not?

Chem Catalyst

• Describe in your own words how molecules move in a solid, liquid and gas.

• Describe what happens to water molecules at the surface to allow them to evaporate.

• Do water molecules break apart into H and O when they evaporate?

Chem Catalyst

• When do you think the first thermometer was invented?

Early 1600’s

• How would you describe the weather outside if you couldn’t use a thermometer?

• What makes the liquid rise and fall in a thermometer?

Lab - “Hot Enough”

• Today we’ll be making our own “homemade” thermometers. By the end of the class, you should be able to explain how a thermometer works on a molecular level.

Chem Catalyst

• Describe what happened yesterday in lab on a molecular level to cause the green liquid to rise up in the straw.

Eureka Videos 4 and 5

Check-In

• Describe what happens to water molecules at the surface during evaporation.

Compressibility of Liquid vs. Gas

Can you compress a syringe full of air?

What about a syringe full of water?

World of Chem Vid 5

• Advance to 13:50 – Liquid nitrogen

• What is the temperature of liquid nitrogen?

• What will happen to the racquetballs when hit with a hammer after being in the liquid nitrogen? Why?

World of Chem Vid 5

• Advance to 17:40 – Bromine

• Bromine exists as a gas at room temperature. What will happen to it as it is cooled down by liquid nitrogen?

Is it possible for a substance to go from a solid to a GAS without becoming a liquid

first?

• http://www.conceptualchemistry.com/index.php?option=com_k2&view=item&layout=item&id=29&Itemid=83

• Forward to 3:29

http://www.conceptualchemistry.com/index.php?option=com_k2&view=item&layout=item&id=29&Itemid=83



School culture survey

1.) In your own words, describe the culture at Thurston (not in terms of race, but in terms of the academic environment). Are students here to learn and succeed academically, or for other reasons?

2.) What role do you play in the culture at Thurston? Do you fit in to the dominant culture you described in the first question, or do you fit somewhere else?

School culture survey

3.) Do you think it’s possible to change the school culture? Explain why or why not.

4.) What changes would you like to see in the culture at Thurston?

Chem Catalyst• Imagine you are trying to

unscrew a metal lid from a glass jar. No matter how hard you try, you can’t seem to unscrew it!

• Would it be better to run the lid under hot water or cold water to help get the lid off? Explain in terms of molecular motion.

Chem Catalyst• How does a suction cup

work? DO NOT just say “suction” – think about what you have to do to the suction cup to make it stick to a surface.

• Why doesn’t it fall off the window/wall you stick it on? What force keeps it there?

What is AIR???Solid, Liquid or Gas?

Is it air made of one element, or a combination of them?

Composition of Air:

- 78 % N2 (nitrogen gas)

- 21 % O2 (oxygen gas)

- 1 % CO2 (carbon dioxide gas and other elements)

Egg in a flask demoBefore During After

Reverse Gravity Demo

Before During After

55 Gallon Drum crush

• http://www.youtube.com/watch?v=JsoE4F2Pb20&feature=endscreen&NR=1

Chem CatalystAir Force

• The tanker in this picture was destroyed by the power of air. What do you think happened to it? Write down your thoughts and ideas.

Air Force Demos!!!• Paper towel submerged in cup• Balloon in bottle (2 students race, one blowing up balloon, one trying to do it in a

flask)• Cup and card (cup filled with water, covered by a cut out of transparency – flip the

cup over and remove hand from bottom and the card stays.• Soda can – fill with small amount of water, heat for a while to build up water vapor, have cold

water bath with ice ready, QUICKLY flip the can over and put into water.

• Balloon in flask – put a small amount of water in flask, heat water so lots of vapor inside, put balloon onto mouth of flask right side up, set aside and watch it cool and suck the balloon in.

• Put partially inflated balloon into bell jar and turn on pump

• Shaving cream – have a watch glass in the bell jar, put shaving cream on, watch expand when pump is turned on

• Drinking straw – just make a drawing

• Funky flask with hole and balloon – if time allows, put balloon inside flask, blow up balloon while cork is removed, then plug in cork and watch balloon stay inflated. Then put water into balloon, and ask students if air pressure is strong enough to push the water out? Unplug cork over a sink or bucket and watch the water fly!

Balloon in round flask demo• What causes the balloon to stay inflated when the cork

is plugged in?

• What will happen to the inflated balloon when the cork is removed? Why?

• What will happen if the inflated balloon is filled with water and the cork is removed? Why?

Chem Catalyst

• Imagine you take an inflated balloon into space with you in a space shuttle. During your first spacewalk outside of the shuttle, you take the balloon with you.

• What will happen to the balloon and WHY!?!?!

Answers to RealACT Practice Science Test #2

1.) B

2.) F

3.) A

4.) H

5.) D

6.) G

7.) D

22.) H

23.) C

24.) G

25.) D

26.) G

27.) B

28.) J

15.) B

16.) F

17.) A

18.) J

19.) A

20.) J

21.) C

8.) F

9.) C

10.) G

11.) C

12.) H

13.) D

14.) G

29.) D

30.) F

31.) C

32.) F

33.) A

34.) J

35.) B

36.) J

37.) B

38.) H

39.) C

40.) J

Intro to 2nd semester

• Check seating chart

• Pick up a new chem catalyst sheet and any other worksheets at the front of the room.

• Take your seat and be quiet.

Refresher on class procedures

• Pick up any worksheets of the day• Turn in any homework that is due into

the turn-in bin• Pick up any returned work• Take your seat and begin working on

the chem catalyst question.• You do not have to copy down the

question, but use complete sentences to answer your question.

If you are absent…

• Check the calendar in the back of the room to see what you missed. Pick up any work you missed.

• Talk to someone you trust about the work and any notes you missed.

• Turn in your work within 3 days, writing “Absent” on the paper.

Few changes to 2nd semester

• Tardy policy• Late worksheet policy - 80% credit on

work done in class that is late. I will accept late daily work up to 2 days from the day it is due.

• Late homework policy is still the same…no late homework will be accepted

• In-class groups - random at first, you’ll set them later.

Grading scale changes

• Tests/Quizzes = 55% (up from S1)

• Daily Work = 25% (down from S1)

• Homework = 12% (up from S1)

• Chem Catalyst = 8% (down from S1)

Chem Catalyst• What do you think would happen to an

inflated balloon if it were suddenly put into outer space where there is no atmosphere?

• When we fly in an airplane we often feel the change in air pressure in our ear canals when our ears “pop.” Explain what you think is going on.

Divide and Document

• Vertical line 2” from left

• Horizontal lines at top and about 5-6 lines from bottom

• Course name, date, and topic in upper right corner

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Example



Write Notes

• The large box is for taking notes.

• Skip a line between ideas and topics.

• Do NOT use complete sentences. Abbreviate whenever possible (&, b/c, b/t, w/, w/out, w/in, , )



Review and Clarify

• Review the notes as soon as possible after class.

• Pull out main ideas, key points, dates, and people, and write these in the left column.



Summarize

• Write a summary of the main ideas in the bottom section.



Study your notes

• Re-read your notes in the right column.

• Spend most of your time studying the ideas in the left column and the summary at the bottom. These are the most important ideas and will probably include most of the information that you will be tested on.



Notes

• Air Pressure: The force caused by the molecules of the gases hitting the walls of the container they are in.

Online simulationhttp://intro.chem.okstate.edu/1314F00/Laboratory/GLP.htm

Quick Review

• How do gases differ from solids and liquids in terms of:– Particle movement?

– Overall organization? (which form is the most ordered? Least ordered?)

Question of the day…

• How do we measure pressure?

Manometers and Barometers

Instruments Used to Measure Pressure

Manometers

• A manometer is comprised of a bulb containing a gas and a U-shaped tube.

• The U-shaped tube is partially filled with mercury.

Manometers

• Depending on the pressure of the contained gas, the mercury shifts.

• The difference between the heights of the mercury on each side of the tube is a measure of the pressure of the gas.

Manometers

• When gas pressure is greater than atmospheric pressure, the mercury is pushed toward the open end.

• When gas pressure is less than atmospheric pressure, the mercury is pushed toward the gas reservoir.

• What is doing the “pushing?”

Practice Problems

105mm

75mm

Proom = 760 mmHg

Practice Problems

Proom = 760 mmHg

90mm

82mm

Work on the first 2 problems on your worksheet

Chem Catalyst• The THS Eagle started out in

Redford, MI at an elevation of 600 ft above sea level. He flew to Denver, CO which has an elevation of 5,280 feet.

• Which city has greater air pressure and WHY?

Redford

Denver

Please get a CALCULATOR

• There are located at the back of the room

Chem Catalyst

• Where is there greater air pressure – on the ground, or at 35,000 ft. where airplanes fly?

• As you take off and land in an airplane, your ears “pop”. What do you think causes your ears to “pop”?

Sea (or Tower) of AirPressure

• Which situation do you think has more pressure being applied?

• 1. A sledgehammer hitting one nail?• 2. A sledgehammer hitting a bed of nails?

Pressure Definition

• Pressure is defined as the force exerted in a given area; force for every unit of area.

• Units of Force: Units of Area:

• Pressure =

Question?Pressure

• Which situation do you think has more pressure being applied?

• 1. A sledgehammer hitting one nail?• 2. A sledgehammer hitting a bed of nails?

Online Videohttp://video.google.com/videoplay?docid=4923611316489753520&ei=FYx7ScvCKpPiqQLO77HUCA&q=bed+of+nails

Scroll forward to 2:00

http://video.google.com/videoplay?docid=4923611316489753520&ei=FYx7ScvCKpPiqQLO77HUCA&q=bed+of+nails

http://video.google.com/videoplay?docid=4923611316489753520&ei=FYx7ScvCKpPiqQLO77HUCA&q=bed+of+nails

Tower of Air worksheet

Barometers

• A barometer consists of a tube filled with mercury that is placed, upside-down, in an open dish of mercury.

• The top of the tube is a vacuum.

• The bottom of the tube is open to the atmosphere.

Barometers and units of pressure

Units of Pressure:

“760 mm of mercury”, or

760 mmHg

What is causing this pressure?

Is the pressure here in Michigan the same as it would be near the top of Mt. Everest?

Barometers and units of pressure

Units of Pressure:

“760 mm of mercury”, or

760 mmHg

Why do you think mercury is used in the column instead of another liquid (like water?)

Hint: Density of mercury = 13.6 g/mL

Density of water = ____ g/mL

Does air really cause enough force as it’s pushing down?

Let’s try something…

Units of pressureAtmospheric Pressure at sea level = 1 “atmosphere” (atm)

1 atmosphere (atm) = 760 mm Hg =

14.7 pounds per square inch (psi) =

101.3 kilopascal (kPa) = 101,300 Pascal

Barometers

• There is a reservoir of mercury at the bottom of each barometer.

• Depending on the atmospheric pressure, the level of fluid in the barometer can RISE or FALL.

• The weather report may say, “The pressure is 30.15 inches and falling.”

• What do you think this means?

Check-In: Thought experiment

• What happens if you take a cup of water, stick a straw into it, plug the top end, and take out the straw?

• Explain in terms of air pressure.

Chem Catalyst

What happens to your ears if you roll down your windows while driving on the highway?

Why does this happen?

ChemCatalystPressure

GET A CALCULATOR PLEASE• Which situation do you think has more

pressure being applied?• 1. A sledgehammer hitting one nail?• 2. A sledgehammer hitting a bed of nails?

Units for Pressure

• Just like temperature (Celsius, Fahrenheit, Kelvin), there are different units for pressure.

• Standard Pressure = 1.0 atm (atmosphere)

• 1.0 atm = 760 mmHg = 14.4 psi = 101.3 kPa

• All the above units are equivalent to each other – i.e. 1.0 atm = 14.4 psi or 101.3 kPa = 760 mmHg

Converting Units of Pressure

Car tires normally have a pressure of about 32 psi. Convert this to units of kPa.

• 1.0 atm = 760 mmHg = 14.4 psi = 101.3 kPa


The pressure on top of Mt. Everest is around 40 kPa. Convert this to units of mmHg.

• 1.0 atm = 760 mmHg = 14.4 psi = 101.3 kPa


The pressure at the deepest part of the ocean (Mariana Trench) is about 15,750 psi. How many atm would this be?.

• 1.0 atm = 760 mmHg = 14.4 psi = 101.3 kPa

Pressure vs. Volume

If you push the syringe down, what happens to the

pressure?

What happens to the volume?

Get your calculator from the back

Chem Catalyst

• You take a syringe filled with gas and plug the end.

1.) Is the pressure inside the syringe the same or different than it is from the outside? How can you tell?

2.) What is causing this pressure?

3.) What can we do to change the pressure inside the syringe?

Let’s play with syringes

Online simulationhttp://intro.chem.okstate.edu/1314F00/Laboratory/GLP.htm

WHY does the pressure change as the volume is changed?

http://intro.chem.okstate.edu/1314F00/Laboratory/GLP.htm

Try this…• How can we keep the amount of gas in the

syringe constant?• Set your syringe plungers to 60 mL and plug the

end of the syringe.• Pull out the plunger completely.• Keeping your finger over the end of the syringe,

try to put the plunger back to 60 mL.• Why can’t you get it back to 60 mL?• Today’s experiment, you are working with closed

syringes. Do NOT remove the plungers.

What are our variables?

• Dependent variable (what we are studying today):

• Independent variables (what can we vary to change the dependent variable):

Chem Catalyst

1.) Sketch a graph showing the relationship between pressure and volume, being sure to label the axes.

2.) What variables did we hold constant in our pressure/volume lab on Friday?

Chem Catalyst• If you have a gas in a syringe,

what are three things you can do to change the pressure of the gas?

• If the pressure in a syringe is 20 psi and the volume of gas is 40 mL, what happens to the pressure if the volume is decreased to 20 mL?

Particle view of what’s causing pressure (online

simulation)

Boyle’s Law

P•V = k

P1 •V1 = P2 •V2

P 1

V

P k1

V

Let’s rearrange Boyle’s Law

P1 •V1 = P2 •V2

Boyle’s Law conversion factor

V1V2

1

V1V2

1

Case 1: Volume in a closed syringe gets larger. What happens to pressure?

Case 2: Volume in a closed syringe gets smaller. What happens to pressure?

Boyle’s Law conversion factor

P1P2

1

P1P2

1

Case 1: Pressure in a closed syringe gets larger. What happens to volume?

Case 2: Pressure in a closed syringe gets smaller. What happens to volume?

Please get a calculator

Chem Catalyst• You have a gas in a closed container that

occupies 120 mL and has a pressure of 1.5 atm. If the gas was compressed to a new volume of 40 mL, what is the final pressure?

Follow these steps….a.) Knowns and unknownsb.) Constantsc.) Cause/Effectd.) Calculate

• Convert the new pressure to units of psi • (hint: 1 atm = 14.7 psi)

Chem Catalyst• You have a gas in a closed container that

occupies 120 mL and has a pressure of 2 atm. If the gas was compressed to a new volume of 40 mL, what is the final pressure?

• What variables are being held constant in the syringe of gas?

• Convert the new pressure to units of psi (hint: 1 atm = 14.7 psi)

• You have a gas in a closed container that occupies 100 mL and has a pressure of 3 atm. What would be the new pressure if the gas has a new volume of 30 mL?

• You have a gas in a closed container that occupies 70 mL and has a pressure of 2.5 atm. What would be the new pressure if the gas has a new volume of 85 mL?

• You have a gas in a closed container that occupies 200 mL and has a pressure of 4 atm. What would the new volume be if the gas has a new pressure of 5 atm?

• You have a gas in a closed container that occupies 20 mL and has a pressure of 7 atm. What would the new volume be if the gas has a new pressure of 3 atm?

Practice Problems• You have a gas in a closed container that

occupies 50 mL and has a pressure of 2 atm. What would be the new pressure if the gas was compressed to a new volume of 30 mL?

1. Draw a picture using “whooshies.”

Chem Catalyst• A gas in a closed syringe has an initial volume

of 30 mL and a pressure of 1.5 atm. The syringe plunger is pulled out to a volume of 40 mL. What is the new pressure?

• What are the knowns and unknowns?

• What’s held constant?

• What’s the cause and effect?

• Calculate the new pressure.

• If 1 atm = 14.7 psi = 760 mmHg = 101.3 kPa,convert the new pressure into mmHg.

Chem Catalyst

• Which has a constant volume, the pop bottle or the syringe inside?

• Which has a constant number of particles, the pop bottles or the syringe inside?

• How does the demonstration show pressure vs. number of particles AND pressure vs. volume?

• 1.) Get out any notes or assignments you want to use on the quiz

• 2.) Get a calculator

• 3.) Take your seat and get ready to ace this quiz!!!

Chem Catalyst• A closed syringe contains 3 “puffs” of air and has an

initial volume of 20 cm3 and a pressure of 30 psi. Without changing the temperature, the volume is increased to 45 cm3. What is the new pressure?

• What are the knowns and unknowns?• What’s held constant?• What’s the cause and effect?• Calculate the new pressure.• If 1 atm = 14.7 psi = 760 mmHg = 101.3 kPa, and if

1 kPa = 1000 Pa, convert the new pressure to Pa.

ChemCatalyst

• In Gas Law Lab 1, Feeling Under Pressure:– What was the independent variable?– What was the dependent variable?– What variables were held constant?

• In Gas Law Lab 2 (today’s lab)– Our independent variable is the amount of gas (n)– Our dependent variable will be the pressure.– What variables will be held constant?

ChemCatalyst

You decide to pump up your car tires one day.

1.) What variables are changing when you pump up your tires? (P, V, T or # of molecules)

2.) What variables are NOT changing when you pump up your tires? (P, V, T or # of molecules)

Pre-lab discussion

• How can we adjust the amount of gas in the syringe?

• How does the density of the air in the syringe compare with the air outside the syringe?

• How can we keep volume constant during the experiment?

P vs. n Lab

• Constant Volume and Temperature

• Our constant volume will be 10 mL.

• Our value of “n” will be counted in “puffs” of air.

• Every 10 mL of gas in the syringe will be 1 “puff” of air.

ChemCatalyst• Get a calculator

• Take out your ChemCatalyst

1.) Draw a graph showing the relationship between pressure and volume. Label the axes.

2.) Draw a graph showing the relationship between pressure and # of molecules. Label the axes.

ChemCatalyst• Go get YOUR calculator from the back.• 5 “puffs” of gas at 20 Celsius has a pressure of 1.5

atm and a volume of 42 mL. What is the new pressure of the gas when the volume is increased to 66 mL? – What are knowns and unknowns.– What’s constant?– What’s the cause and effect?– Calculate– Draw before and after pictures

Convert your answer to units of kPa.

(Hint: 1 atm = 101.3 kPa)

Chem Catalyst

• A gas which occupies 100ml is at an initial temperature of 25 degrees Celcius. The gas is cooled to 0 degrees Celcius. What is the new volume? – What are the knowns and unknowns in the

problem?– What is constant?– What’s the cause and effect?– Calculate the new volume.– Draw a particle diagram

Chem Catalyst

• Based on the lab from yesterday, if we double the number of “puffs” in a syringe, what will happen to the total pressure?

• What will happen to the total pressure if we triple the number of “puffs”?




Chem Catalyst• Look at the following pictures. Which

variables are held constant? Which variables are changing? Which picture has a higher pressure? How do you know?

Notes

• P and n are “directly proportional”

• Ratio P/n should be constant

• If independent var. doubles, dependent var. also doubles. If I.V. triples, D.V. also triples, etc.

• Graph goes through the origin, (0,0)

Check-In

• What would happen to the pressure of a gas if you decreased the volume AND increased the number of molecules?

• What would happen to the pressure of a gas if you increased the volume AND decreased the number of molecules?

ChemCatalyst5.5 puffs of air have a pressure of 900 mmHg. What

is the pressure when three puffs of air are removed?

• a.) Knowns and unknowns• b.) Constants• c.) Cause and effect• d.) Do the calculation!

e.) Convert to units of psi (14.7 psi = 760mmHg)

Chem Catalyst

• You have 3 units of a gas at 25°C and a pressure of 700 mmHg. You add 6 units of gas to the container. Assuming constant volume, what is the new pressure?

• A) Knowns and unknowns.• B) Constants.• C) Cause and effect.• D) Calculate!• E) Convert to units of psi (14.7 psi = 760 mmHg)

Chem Catalyst

• A gas in a sealed metal container is heated up from 20 to 100 °C.

1.) Draw two particle diagrams to show what the particles looked like before and after they were heated up.

2.) Which box will have a higher pressure? Why?

3.) What is held constant?

Chem Catalyst

• Think about a popcorn kernel that is put into the microwave. What is going on inside the popcorn kernel?

1.) What variables are held constant inside the kernel?

2.) What variables are changing?

3.) What causes the popcorn kernel to “pop”?

World of Chem Vid 5

• Advance to 6:20 – Gas in sealed container

• What will happen to the pressure of the gas as it is heated? Cooled?

• What causes this pressure?

New Experiment

• Dependent Variable:• Independent Variable:• Constants:

• How do you think the temperature will affect the pressure of a gas in a sealed container?

P vs. T

New temperature scale

• Kelvin scale, or “absolute temperature scale”

• Just “Kelvin”, not “degrees” Kelvin

• K = °C + 273

• 0K = -273 °C is called Absolute zero

• At absolute zero, all particles stop moving.

Notes

• P and T are “directly proportional” only for Kelvin temperatures

P T

• Ratio P/T should be constant only for T in Kelvin.

Notes

• “Standard” conditions:– Pressure = 1 atm– Temperature = 273 K

• “STP” means “Standard Temperature and Pressure”

Chem Catalyst

• You have 3 units of a gas at 25°C and a pressure of 700 mmHg and a starting volume of 23 ml. What is the new pressure if you adjust the volume to 30 ml?

• A) Knowns and unknowns.

• B) Constants.

• C) Cause and effect.

• D) Calculate!

• E) Convert to units of psi

(14.7 psi = 760 mmHg)

ChemCatalyst

• Which is a higher temperature, -20 ºC or240 K? How do you know?

• A student claims the temperature on Pluto is - 58 Kelvin. Do you agree or disagree? Why?

ChemCatalyst

• Get a calculator please

• Imagine you go to the grocery store to buy some biscuits (Grands, for example). You go to another store afterwards and leave your biscuits in the car. Oh yeah, it’s summertime and VERY hot in your car.

• What might happen to the biscuits in your car and WHY???

Biscuit bullet Mythbusters

http://www.youtube.com/watch?v=1pQwB1NDwGA

ChemCatalyst

Imagine there are two baths with water in them. One of them has a thermometer which reads 300 K, the other has a thermometer which reads 390 K.

Which would you rather take a bath in? Convert the temperatures from Kelvin to Celcius.

K = Celcius temp + 273

Chem Catalyst Review

1.) A fixed amount of gas in a sealed container has a temperature of 25 ºC and a pressure of 15 psi. The container is heated up to a temperature of 200 ºC. What is the new pressure?

2.) A gas in a closed syringe has an initial volume of 30 mL and a pressure of 1.5 atm. The syringe plunger is pulled out to a volume of 40 mL. What is the new pressure?

3.) You have 3 puffs of a gas at 25°C and a pressure of 700 mmHg. You add 6 puffs of gas to the container. Assuming constant volume, what is the new pressure?

ChemCatalyst

• Consider a gas at constant pressure in a flexible container (like a balloon or a basketball).

1.) If we increase the temperature of the gas, what happens to the volume? Decrease temp?

2.) How do you think volume and temperature are related in a gas?

Short video of gas in a balloonhttp://video.google.com/videoplay?docid=-8214698528766059695&ei=XuF8ScaOC4vCrQKZmOy3BQ&q=balloon+liquid+nitrogen

http://www.youtube.com/watch?v=ZvrJgGhnmJo

http://video.google.com/videoplay?docid=-8214698528766059695&ei=XuF8ScaOC4vCrQKZmOy3BQ&q=balloon+liquid+nitrogen

http://video.google.com/videoplay?docid=-8214698528766059695&ei=XuF8ScaOC4vCrQKZmOy3BQ&q=balloon+liquid+nitrogen

Molecular workbench simulation

How would we draw a graph of the relationship between V and T?

Notes

• V and T are “directly proportional” only for Kelvin temperatures

V T

• Ratio V/T should be constant only for T in Kelvin.

Chem Catalyst• A gas held at a pressure of 1 atm has a

temperature of 25 ºC and a volume of 50 mL. The gas is heated up to 50 ºC. What is the new volume?

• What are your knowns and unknowns?• What is held constant?• What is the cause and effect?• What is the new volume?• Draw a before and after picture.

Chem CatalystGO GET YOUR CALCULATOR FROM THE

BACK.

1.) Write “Egg in flask” demonstration for the question

2.) How can I get the egg to go into the flask with only a match?

3.) How can I get it out once it’s inside?

ChemCatalyst

1.) What would be the new volume if 100 cm3 of gas at 25ºC and 0.7 atm pressure were changed to standard conditions of temperature and pressure?

a.List knowns and unknowns

b.List constants

c.Cause and effect

d.Calculate

ChemCatalyst

• Get YOUR calculator from the back.

• What would be the new volume if 45 cm3 of gas at 100ºC and pressure of 800 mmHg were heated to 200ºC and the pressure was reduced to 600 mmHg?

a.) Knowns and unknowns

b.) Constants

c.) Cause and effects (there are two!)

d.) Calculate!

Chem Catalyst• What would be the new temperature of a

gas at 80ºC and pressure of 9 psi if the pressure changed to 13 psi?

• List the knowns and unknowns.

• What is constant?

• What is the cause and effect?

• Calculate.

• Draw a particle diagram

ChemCatalyst• What is the relationship between pressure

and volume? Graph?• Pressure and # of particles? Graph?• Pressure and temperature? Graph?• Temperature and volume? Graph?• What determines the speed of gas

particles?• What causes the gas pressure?

Let’s make some observations about the gas simulationhttp://intro.chem.okstate.edu/1314F00/Laboratory/GLP.htm

(use particle tracking)What do you notice about the motion of the particles and how they collide?


Kinetic Molecular Theory

• Three tenets (principles) of the KMT: Gas particles…– are in constant motion, move in straight

lines, and move until they collide with another particle or a wall

– experience elastic collisions (energy is not lost)

– do not stick to other particles.

Whiteboarding session• Groups 1-3: P vs. V relationship• Groups 4-6: P vs. n relationship• Groups 7-9: P vs. T relationship

• Draw a curve describing the relationship making sure to label axes.

• Pick 3 points on the curve and draw 3 pictures.

• Give 1-2 physical examples of a situation in real life that shows the gas law relationship.

Chem Catalyst

• Assuming that pressure and number of particles is constant, what happens to the volume of a gas if it’s temperature is decreased?

• Assuming that volume and temperature are constant, what happens to pressure as you increase the number of particles?

• Write down all units for pressure you know.

• Write down all units for volume you know.

Situation 11.) What changed?2.) What stayed constant?3.) What kind of problem is it?4.) What is the cause and effect?

ChemCatalyst1.) What changed?2.) What stayed constant?3.) What are the cause(s) and effect(s)?

ChemCatalyst1.) What changed?2.) What stayed constant?3.) What is the cause and effect?4.) Can you predict what will

happen to the pressure?

Before After

ChemCatalyst1.) What changed?2.) What stayed constant?3.) What is the cause and effect?

Before After

Create-A-Problem!•In your group, you will design a problem for one of the 6 situations we just looked at.

On your whiteboard…….•Draw the whooshies and boxes for your problem •Write out the problem (like the ones you have been solving in class)•The rest of the class has to solve your problem!

•Sample problem:A gas in a sealed container has an initial (temp, pressure, volume, # particles) of ________ (units for temp, pressure, volume, # particles). The gas changed to ________ (units for temp, pressure, volume, # particles). What is the final (temp, pressure, volume, # particles) for the gas?

ChemCatalyst

1.) Write all the units you know for volume (V), pressure (P), temperature (T) and # of molecules (n).

2.) What is the relationship between all of these variables?

- P vs. V

- P vs. n

- P vs. T

- V vs. T

ChemCatalyst

• Draw the graph for each of the following relationships (label the axes and include units)

- P vs. V

- P vs. n

- P vs. T (Celcius)

- P vs. T (Kelvin)

- V vs. T (Kelvin)

What is the cause and effect for each relationship?

ChemCatalyst

GRAB YOUR CALCULATOR.

1.) A closed syringe has 35 mL of gas inside at a pressure of 800mmHg and temperature of 70ºC. What will the final temperature have to be if volume is decreased to 20mL and pressure changes to 600 mmHg?

ChemCatalyst

GRAB YOUR CALCULATOR.

Current atmospheric pressure is at

757 mmHg. Yesterday it was about

747 mmHg. Later tonight a storm is coming and the pressure will drop to around 730 mmHg. What will the pressure be tonight in kPa?

Hint: 101.3 kPa = 760 mmHg

ACT Writing Prompt

Currently there is much debate in the United States regarding how people should be taxed on their income. Some argue that everyone, regardless of income level, should be taxed the same percentage. Others argue that people who make more money should be taxed more, since they have the ability to pay more in taxes. In your opinion, should people be taxed according to their income level?

Chem CatalystPrepare for battle - get your calculator.

• You have a jar of air collected at sea level and a jar of air collected on top of Mt. Everest.

1.) Which jar will have more air molecules inside?

2.) Which jar will have a lower pressure inside?

Chem CatalystReview

• How does a hot air balloon work?• Describe what happens to molecules as the air in a hot air

balloon is heated up. Does the amount and mass of the air in the balloon change? What happens to its volume? What happens to the density of the gas?

• Why does the hot air balloon float?• Why can’t balloon rides happen when the temperature is

very hot outside?

Chem CatalystCandle Lab

• Describe everything that you can think of that happens to the air around a candle flame.

• What do you think will happen if you place a candle in a dish of water, light it, and place a beaker upside-down over the candle?

Today’s lab

• On a blank sheet of paper write down the following for today’s lab:– Write a set of detailed observations when

performing the experiment. Make a note of every little thing that happens. Do bubbles form? Does the candle go out? When exactly does the candle go out?

Pictures for today

• Draw three pictures of today’s lab. – Picture 1: What do the air molecules look

like right next to the candle flame? Are they moving fast or slow? Are they close together or spread apart? What do the air molecules look like in the beaker before putting it over the flame?

Pictures

• Picture 2:– What do the air molecules look like in the

beaker with the candle lit inside it? What do the air molecules look like outside the beaker? How does the pressure inside the beaker compare with the pressure outside the beaker?

Pictures

• Picture 3:– What do the air molecules look like in the

beaker after the candle has gone out? How do they compare with the air molecules outside the beaker? How does the pressure inside the beaker compare with the pressure outside of the beaker? What is “pushing” the water?

Chem CatalystCartesian Divers

• Why is it that a solid piece of aluminum sinks in water, while an aluminum row boat like this one floats?

Definition

• Buoyancy: an upward acting force exerted by a fluid, that opposes an object's weight. If the object is either less dense than the liquid or is shaped appropriately (as in a boat), the force can keep the object afloat.

Buoyancy illustration

• If the bottle was completely filled with water, it would have 10 pounds of force pushing upwards.

Semester #2 Make it count!. Chem Catalyst You have two cups of water – one with COLD water and one...

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Transcript of Semester #2 Make it count!. Chem Catalyst You have two cups of water – one with COLD water and one...