AP Chem – Q2 – week 8 – 21-22 | Mr. Grodski Chemistry

Q2 : Week 8 – 1/9- 1/13

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________________________________________________________________ Jump to: Monday Homework / top

1/9 – Monday – A Day – 2/3a Lab, 4

Main focus –

a) To take a Derivation Quiz

b) To begin a Molecular Mass Gas law lab

c) To Review the gas law homework and collect!

Period 2/3a:

1. Gas Law Derivation Quiz –

Gas Law Equations Derivation Quiz.pdf
View Download

2. Lab 18 – Molecular Mass of an unknown gas.

3. Frozen lipids Demo

Period 4:

1. Gas Law Derivation Quiz

2. Lab 18 – Molecular Mass of an unknown gas.

3. Frozen lipids Demo

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Lab 17 – The Molecular Mass of Unknown Gases.

Lab 17 – Molecular Mass of an unknown gas.pdf
View Download

Two 60 cubic foot tanks of 2 unknown gases are placed on the Lab Cart. One is more dense than air and one is less dense than air. The Molecular Mass of each gas will be determined by using our gas laws.

1. Mass out the plastic 1 Liter Erlenmeyer flask with cap (with air).

2. Determine the mass of the evacuated Erlenmeyer flask.

3. Flush out the flask with unknown holding the flask appropriately to fill it with one of the unknown gases and screw the cap tightly.

4. Mass out the flask with the unknown gas.

5. Determine the mass of the unknown gas.

6. Repeat steps 3, 4, and 5 for the second unknown gas.

7. Fill the flask with water and measure the volume of the filled 1 Liter Erlenmeyer flask.

8. Measure the temperature of the room and obtain the atmospheric pressure of the day.

9. Calculate the Molecular Mass of each gas.

10. Identify the gases based on Molecular Mass.

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1/9 – Monday’s Homework: –

1. Please view the lecture on Daltons Law in any speed but take notes on the derivation:

2. Complete questions 1 and 3 only in the Gas Law worksheet 7 – Daltons Law.pdf worksheet.

And Review with the key or Lecture below.

Gas Law worksheet 7 – Daltons Law.pdf
View Download

Gas law worksheet 7 – Daltons Law Key.pdf
View Download

3. Watch the Daltons Law Demo and Fire syringe demo and complete the form below:

You have a total of three submissions tonight for this form.

1: Daltons Law Derivation

2: Daltons Law worksheet question 1 and 3 review video.

3: Dalton’s Law of Partial Pressure:

3: The Fire Syringe Demo.

3: Daltons Law of Partial Pressure Form:

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End of Monday!

_________________________________________________________________ Jump to: Tuesday Homework / top

1/10 – Tuesday – B Day – 2, 3b Lab/4

Main focus –

a) To complete the Molecular Mass calculations of Lab 17

b) To Review the concepts of Daltons Law and its real life applications

c) To introduce vapor pressure.

Period 2:

1. Lab 17 – review

a) Evaluate Data – Complete calculations and hand in

b) You may have to redo the gas measurement if really off.

c) errors

2. Daltons Law of Partial Pressures –

a) Review of Dalton’s law partial pressure demo’s

mole fraction, volumes fraction, pressure fraction are equivalent due to

V = n * K (Avogadro’s hypothesis)

b) Review of Homework:

Gas law worksheet 7 – Daltons Law Key.pdf
View Download

c) partial pressure ideas

Scuba Tanks, Brooklyn Bridge, and the Romans (lung demo)

Period 3b/4:

1. Lab 17 – complete the lab and calculations – students kept the lab until KMT

2. Review of Homework – Daltons law – better explanation for question 1

3, Did not get to Scuba or Brooklyn Bridge applications

Daltons Law Applications:

Today’s Class lecture.

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1/10 – Tuesday’s Homework: –

1. Please complete the following worksheet AND review with the key.

*Remember what is proportionate when gases are in the same container!

Daltons Law Worksheet 2.pdf
View Download

Daltons Law Worksheet 2 Key.pdf
View Download

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__________________________________________________________________________ Jump to: Wednesday Homework / top

1/11 – Wednesday – A Day – 2/3a Lab, 4

Main focus –

a) To Review an advanced AP Daltons Law Problem

b) To identify the strength of IMF in different liquids based on their vapor pressure

c) To define boiling, vapor pressure and distillation

Period 2/3a:

1. Review of Homework:

Daltons Law Worksheet 2 Key.pdf
View Download

2. Complete partial pressure ideas

Scuba Tanks, Brooklyn Bridge, and the Romans (lung demo).

3. Vapor Pressure intro, table H –

a) boiling cold in a baggie

b) liquid nitrogen with an air horn

c) boiling water in vacuum chamber

4. Lab 18 – Molecular Mass of quadrupled distilled Butane – intro

Lab 18 – Purity of Butane – water displacement.pdf
View Download

Vapor Pressure of Water table.pdf
View Download

Period 4:

1. Review of Homework

2. Complete partial pressure ideas

Scuba Tanks, Brooklyn Bridge, and the Romans (lung demo).

3. Vapor pressure intro/ table H

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NOTES FOR Vapor Pressure:

Vapor pressure – slide 8 – 17 in Pressure Intro Presentation – posted at the end of today’s post.

Vapor Pressure is the Force per Area (F/A) created by gas molecules that have just evaporated from the liquid state. This pressure of evaporating liquids depends on how well the molecules of the liquid attract each other. These attractions are called IMF’s (Intermolecular Forces or Attraction).

The stronger the IMF between the molecules in the liquid the MORE that the liquid Resists evaporation AND THUS will evaporate less (at the same temperature) and thus produce LESS vapor pressure.
The strength of the IMF’s are unique for each liquid and thus each liquid has a unique vapor pressure curve.

Another important FACTOR in vapor pressure is the Temperature of the the liquid. Even though each liquid has its own vapor pressure due to its unique strength of IMF’s, ALL LIQUIDS will increase their vapor pressure or evaporating due to an INCREASE in Temperature!!
An increase in Temperature is a result of an increase of energy that is absorbed AND will be used to free molecules from each other by breaking IMF’s.

*IMF’s ARE NOT BONDS!

All liquids have a unique vapor pressure curve based on how strong or weak they ATTRACT each other.

Example: Propanone does not H-bond with itself but water does. Water has Stronger IMF than propanone.

All liquids will increase their vapor pressure with an increase in Temperature.

Example: Water has a lower vapor pressure than Propanone at the same temperature but they will both increase when temperature increases as IMF’s are broken.

Vapor pressure values will increase with increase of temperature

until the vapor pressure EQUALs the Atmospheric pressure!

I like to think of boiling as the temperature which a liquid reached MAX EVAPORATION at a certain atmospheric Pressure. What limits this temperature OR BOILING IS THE Atmospheric Pressure. This means that every liquid can boil theoretically at any temperature! If you look back at Table H, water can boil at 55 degrees Celsius if the Atmospheric pressure is 10 kPa (about .1 atm). Lowering the atmospheric pressure will affect the boiling pint because you will need less vapor pressure to Equal or match the lowered atmospheric pressure. Water will also boil at about 105 degrees when the atmospheric pressure is raised to 120 kPa (about 1.2 atm). To combat this will usually talk about boiling in terms of STANDARD PRESSURE = 101.3 kPa or 1 atm or 760 torr or 14.7 psi. In Table H above the horizontal line going across is the STANDARD atmospheric Pressure, thus when the vapor pressure of any liquid reached that line at standard pressure the temperature of the this boiling point is the NORMAL BOILING POINT. We compare liquids Normal Boiling points!

Larger Normal Boiling Point = Higher IMF’s = Lower Vapor Pressure WATER

Smaller Normal Boiling Point = Lower IMF’s = Higher Vapor Pressure PROPANONE

Distillation of Coke Demo:

A mixture (2 or more substances that are not Bonded together) can be separated physically. A physical separation is one that breaks attractive forces AND NOT CHEMICAL BONDs.

In this demo the water in the Coke mixture retains its unique boiling point because it Is NOT BONDED with any other component. It will reach its maximum vapor pressure (boiling point) at different temperatures than the other components (because water has unique strength of attractive forces that results in a unique vapor pressure) thus water will leave as a gas and then cool to condense into a liquid as its distilled.

I use distilled water for all of my solutions that I make for all of the demos and labs. WHY?

Crude oil Refinery:

This is picture of a gasoline refinery that you can see in New Jersey as you travel south on the New Jersey Turnpike.

This is an example of Fractional Distillation of Crude oil. Like all Distillation it is based on the different boiling points/vapor pressures of the mixtures of liquids that are being separated.

Notice the tubes coming off the columns at different heights. This demonstrates the condensation of the vapors at different temperatures. The higher the gas needs to travel to cool and condense into a liquid the weaker the IMF’s of the liquid in the mixture and the high its vapor pressure.

Remember that boiling temperature (point) is equal to the condensation temperature.

Compounds at that are gases at room temperature are Gases because they have weak attractive forces between them AND THUS they would boil at very low temperatures.

They are gases because they have already BOILED!!!! AND THUS they have extremely high vapor pressures! And thus they must have low NORMAL boiling points because their very high vapor pressures will equal the atmospheric pressure at low temperatures.

So gases have:

1 ) very weak IMF’s (which make the molecules evaporate easier!)

2) High vapor pressure (due to the ease in which molecules evaporate)

3) Low Boiling points (due to the high vapor pressure that reaches atmospheric pressure quickly).

Here is a great example. Nitrogen liquid boils at – 196 degrees Celsius and thus has already boiled and exits as a gas in our atmosphere. Below I have liquid Nitrogen, N₂ (l) which was made by pressurizing Air into a liquid (forcing the nitrogen molecules to attract each other).

Lets add liquid nitrogen to table H and see where it fits!!!

How does liquid nitrogen (red) compare to the other liquids???????

Vapor Pressure Presentation:

Vapor Pressure Demo:

Vapor Pressure Demo 2:

Boiling cold water in a Vacuum chamber: Notice the temperature changes! Evaporation or boiling is an endothermic process due to the high energy molecules leaving the system.

Liquid Smear demo:

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1/11 – Wednesday Homework: –

1. Complete the Vapor Pressure Form posted below:

You may need to use the notes posted above to help if you need help with these concepts which where taught in the summer institute.

Summer Institute vapor pressure lectures: Vapor pressure in general

Table H focus

2. Complete questions of 4 and 2 only in the Gas Law worksheet 7 – Daltons Law.pdf worksheet.

Please do question 4 first and then question 2! This question will connect with Lab 18!!!!

You may need me to model the problems with the video posted below.

3. Review with the key or use the video posted below.

Gas Law worksheet 7 – Daltons Law.pdf
View Download

Gas law worksheet 7 – Daltons Law Key.pdf
View Download

1: Vapor Pressure Form::

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End of Thursday!

3. Question 4 and 2 Reviewed:

1. Vapor Pressure Lecture:

__________________________________________________________________ Jump to: Thursday Homework / top

1/12 – Thursday – B Day – 2, 3b Lab/4

Main focus –

a) To incorporate vapor pressure into Dalton’s law problems

b) To determine the Molecular Mass of Butane by water displacement – Lab 18

Period 2: –

1. Review of vapor pressure concepts

a) boiling cold demo – butane in the baggie

b) Liquid nitrogen in Table H

b) Distillation, IMF’s are weaker than chemical bonds – asphalt, phase changes

2. Lab 18 data collection.

Period 3b,4: –

1. Complete the Vapor Pressure lesson

a) IMF’s are weaker than chemical bonds – asphalt

b) Boltzman Distribution of Kinetic Energy for vapor pressure

c) Distillation

d) boiling cold demo/baggie with quadruple distilled butane/Air horn Demo

2. Lab 18 data collection.

Butane – boiling cold demo –

Air Horn Destroyed by Temperature: Pressure is proportionate to Temperature : Gay-Lussacs Law OR the vapor pressure of the can is decreased!!!!!!

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Lab 18 – The Molecular Mass of Quadrupled Distilled Butane by water displacement.

Lab 18 – Purity of Butane – water displacement.pdf
View Download

* make sure students do not invert the can to get the gas as it will dispense liquid that will add to the mass lost but not add significantly to the volume. (liquids have a MUCH smaller volume that a gas)

Vapor Pressure of Water table.pdf
View Download

A can of quadrupled distilled butane (by fractional distillation) will be collected by water displacement. The mass of the butane will be determined by the difference of the mass before and after dispensing the gas.

Butane, C₄H₁₀ will not dissolve or react with water and thus is an appropriate candidate for water displacement. The volume will be measured using a eudiometer tube and the total pressure will INCLUDE water vapor as water has a vapor pressure at all temperatures.

Molecular Mass of Butane Lab calculations explained:

Live Stream of the lab (last year):

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1/12 – Thursday Homework: –

1. Please complete the Gas Law Stoichiometry 2015.pdf worksheet and review with the key.

Think about how we solved the homework Tuesday night using Dalton’s Law of Partial Pressure and the manometer (column of water).

Gas Law Stoichiometry 2015.pdf
View Download

Gas Law Stoichiometry key p.pdf
View Download

_________________________________________________________________ Jump to: Friday Homework / top

1/13 – Friday – A Day – 2/3a Lab, 4

Main focus –

a) To Perform Lab 18 – Molecular mass of the quadupled refined butane.

b) To compare and contrast phase diagrams of water and carbon dioxide.

Period 2/3a: –

1. Perform Lab 18 – water displacement.

2. Limitations to Lab 18

a) How to avoid the manometer part!

b) water displacement limitations

3. Vapor pressure to Phase Diagrams, refrigerators, air conditioners (did not quite get to this)

Phase diagram review:

a) Critical Point

b) water vs. carbon dioxide

c) Freeze dried / astronaut food

d) ICE SKATING/ the titanic

Period 4:

1. Complete Lab 18 calculations

2. Limitations to Lab 18

a) How to avoid the manometer part!

b) water displacement limitations

3. Vapor pressure to Phase Diagrams, refrigerators, air conditioners –(did not quite get to this)

Phase diagram review:

a) Critical Point

b) water vs. carbon dioxide

c) Freeze dried / astronaut food

d) ICE SKATING/ the titanic

Water Phase Diagram:

Comparison or water to carbon dioxide:

Use Phase Diagram lesson:

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Lab 18 – The Molecular Mass of Quadrupled Distilled Butane by water displacement.

Lab 18 – Purity of Butane – water displacement.pdf
View Download

Vapor Pressure of Water table.pdf
View Download

Molecular Mass of Butane Lab calculations explained:

Live Stream of the lab (last year):

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1/13 – Weekend Homework: –

1. Complete Phase diagram worksheet and review the answers with the key that is on the same worksheet. You will probably need to review the concept with the phase diagram worksheet i have posted a lecture below:

Solutions 1a – phase diagrams.pdf View Download

2. We are moving into the last topic of Gas Laws.

We have been describing how the different variables affect each other with the derivation of our gas laws but we have not explained why gases behave this way. Gas behavior is explained through the Kinetic Molecular Theory and it is best understood through ANOTHER Derivation!!

a) Please watch me derive the Kinetic Molecular Theory formulas in the video below Take notes and follow along with me.

I will give you the assumptions, Governing Equations, and the symbols.

I will give you some of the derivation in a skeleton format to help you complete it.

b) Study the derivations as you will be given a quiz tomorrow on the derivations. I cannot believe that am doin this but here is the quiz that you will take Tuesday:

Kinetic Molecular Theory Classwork Derivation.pdf

View Download

3. Please view the notes below on why our Universal Gas Constant for equations from the Kinetic Molecular Theory equations has a different value.

4. Please complete just the front page of the Gas Law worksheet 6 – kinetic energy-grahams law.pdf worksheet and Review with the key but I suggest you follow along with me in the video below.

Gas Law worksheet 6 – kinetic energy-grahams law.pdf
View Download

Gas Law worksheet 6 – KEY- kinetic energy-grahams law.pdf
View Download

5. Please complete the Form that will be posted by Saturday (making a new form!) on the general concepts from the derivations of the Kinetic Molecular Theory and the Gas Law worksheet 6 – kinetic energy-grahams law.pdf worksheet.

1. Phase Diagram Lecture:

End of week 8!

2. Kinetic Molecular Theory Derivations:

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3. Kinetic Molecular GAS law Constant (R) NOTES :

In Kinetic Molecular Equations – (Used to help describe why gases behave according to the ideal

gas law and all of its derived equations: M = dRT & d = PM

P RT

Kinetic Molecular Equations are centered around Kinetic Energy formula, KE = 1/2 mu²

and thus are centered around the SI unit of energy = Joule.

Thus our Kinetic Molecular equations must have terms or units that reflect equivalents in Joules.

Remember from experimental evidence PV = nRT or R = PV

and we have been using .08206 (atm L)

(mole K)

as our Gas Law constant (proportionality constant) and you have learned that you must be in same units for your variables as your ideal gas law constant, R otherwise units do not cancel and your calculation will be in error.

In Kinetic Molecular Equations we cannot use this value of R

that has uses Pressure (atm) and Volume (V) in its Numerator.

We need a value of R that uses Joules instead in order to reflect the KE that is part of the derived Kinetic Molecular Equations that we derived.

KE per mole = 3/2 RT Urms = √3RT

Molar Average KE Root Mean Squared Speed M

This R cannot be the same value as we have been using as it needs to reflect Joules (Energy).

Well fortunately, P x V (the numerator in R) actually can equal Joules if we change the units of

Pressure from atm to Force/Area and Volume from L to meter³ (length x width x height):

Force = mass x acceleration due to gravity

Kg x meter/sec²

Area = meter²

P x V = Energy

force/area length x width x height

Force x meter³

meter²

( Kg x meter/sec² ) x (meter³ ) = Kg meter² = Joule

meter² sec²

So with our Kinetic Molecular equations we use R = 8.31 J _

mol K

This is given in our reference tables:

Also because a joule is really a Kg meter² / sec² then mass must be in Kg!

From your Reference Tables:

4. Front page of the Kinetic Energy – Grahams Law worksheet:

5. Derivations and Concepts of the Kinetic Molecular Theory Form::

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End of Week 8!