Week 1 – Archive – week 1 – 19-21
==Week of 9/4 – 9/6
*Please Refresh as I update and make daily changes to this page.
9/4 – Wednesday – period 2/3
1:Collect Summer Assignment redox packet – and Labs by Institute students
2: Poll/ Remind
3:Explained the homework/class website/communication/assign seating 😉
_______________________________
Using printer out of class:
My classroom printer is web – connected and has its own email address. Email files to your printer to print from anywhere at anytime.
My classrooms email address:
opfec23onra95@hpeprint.com
Write an email to the following address and then attach file to print.
_______________________________________
Demo intro: AP Biology = proteins
AP Chemistry = Coulombs Law = Everything chemistry is Coulombs Law!
4: Demos:
today’s demos:
A) Whoosh Bottle: ethanol + O2 —> CO2 + H2O
Combustion, redox, oxidizing agents or oxidizers
Coulombs Law: introduction = explains why oxygen is a good oxidizer!!!
B) Book – why not
C) Elvira the outermost Electron!
5. began discussion of Redox, Big atoms (metals) vs. Small atoms (nonmetals) and their varying ability to lose (oxidize) or gain (reduce) electrons.
a) atomic radii
b) Coulombs Law: introduction = explains why oxygen is a good oxidizer!!!
c) Demo intro: AP Biology = proteins
AP Chemistry = Coulombs Law = Everything chemistry is Coulombs Law!
d) Oxidative Phosporylation – anaerobic respiration with S instead of O. F vs O,
Gold vs Na?
Spontaneity and Free Energy was introduced.
Did not get too today for either class:
Gun cotton – Cotton spheres that have the oxidizing agent embedded into the cotton so that all of the cotton’s carbon can react with oxygen. There is no unreacted carbon.
Normal cotton is limited by its reaction rate with oxygen in the air on the outer edge of the cotton. (burns outside in). There is plenty of unreacted carbon thus its incomplete combustion.
We would not say that Gun cotton is more spontaneous. It is just has more availability to the other reactant, Gasoline reacts spontaneously with air even though it may not be reacting in a gas can.
C6H10O5 + 6O2 = 6CO2 + 5H2O
Gun Cotton Presentation:
Today’s Whoosh Bottle demo:
Whoosh bottle with a twist:
6: LAB Activity 1 – Making of batteries (voltaic or galvanic cell) – last 15 minutes
In this Lab each lab group will make a pair of voltaic cells that if successfully created will power a 3 volt transistor radio.
a) Made one voltaic cell and identifies anode, cathode and tested voltage.
Identified the spontaneous process with positive volts
wrote half reactions, identified ox and red agents.
LAB 1 – Voltaic Cell.pdf
period 4 –
1:Collect Summer Assignment redox packet – and Labs by Institute students
I forgot to collect your work today. Please place in the purple crate of fun tomorrow.
2: Poll/ Remind
3: Explained the homework/class website/communication/assign seating 😉
4. began discussion of Redox, Big atoms (metals) vs. Small atoms (nonmetals) and their varying ability to lose (oxidize) or gain (reduce) electrons.
a) atomic radii
b) Coulombs Law: introduction = explains why oxygen is a good oxidizer!!!
c) Demo intro: AP Biology = proteins
AP Chemistry = Coulombs Law = Everything chemistry is Coulombs Law!
today’s demos: Did not get these demos today for period 4
Wednesday 9/4 HW:
1. Please fill out the personal History Form below(due tomorrow):
2: this activity using the Safety Contract I gave you and the form below
(this is due Friday 9/7 with parental signature)
Personal History Sheet:
Safety Contract Video activity instructions and Form.
(this is due Friday 9/6 with parental signature)
In this activity, you will write the safety rule (just one sentence) ,its number from the safety contract (that I gave you and is posted below), AND WHERE IN THE VIDEO (:y timecode) that is demonstrated in four safety videos. You need 10 different safety rules and you must use 4 out of the 6 videos. This means if you find 7 in the first video you
will need 1 each from the three others to successfully complete the activity. There are many other combinations but
you must use 4 videos and you must have 10 different Safety rules written.
Let me restate: You must find 10 unique safety rules throughout the four of the six videos of your choosing.
YOU MUST ALSO IDENTIFY BY TIMECODE WHERE IN THE VIDEO THE SAFETY RULE IS BEING
DEMONSTRATED, DISCUSSED, OR INFERRED.
Example of a COMPLETE answer: 1: Jefferson High VIDEO – #45. Examine glassware before each use. (3:23)
I know what #’s each video covers and where thus will grade your work based on this accuracy.
Safety Video Playlist – There are six videos in this playlist (which is also available in the youtube channel). You must choose 4 of the six videos in the playlist below. To select the video from the playlist click on word icon on the upper left corner to toggle between the list and the video
selected.
As you may have figured it might be easier to write you responses in a word doc then cut and paste
it into the form when you are done. This way you have a record which might come useful if there is a issue with submitting.
9/5 – Thursday – Period 2
1. *Gun Cotton demonstration
2. The redox reaction of Na and Cl2.
Viewed my video of the reaction:
Molecular and Ionic compounds/half reactions/ STABILITY
Mr. Stable/ Spontaneity
3: Daniell cell Note taking (Did Not Finish – I will tomorrow)
A: Parts of Voltaic Cell; Redox half reactions; Salt Bridge, flow of ions, flow of electrons
Voltage vs Amperage. Derivation of Energy and Voltage.
Spontaneity – Directionality of chemical reactions – based on Gibbs Free Energy
LeChatelier’s Principle as applied to Voltaic Cells
B: Reduction potentials = Overall best predictor and measure of the ability to oxidize or reduce.
Determination of net potentials
period 3/4 – Grade 10 assembly for 20 minutes?
1. Finish Redox basics/demo:
*Demo Book, Gun cotton demos (redox), whoosh bottle bottle demos were not done
Electron transport system, F vs O2 , S vs O as final electron acceptor,
Na vs Cu for pipes, Gold inactivity
spontaneity and free Energy/ pathway of energy/ voltage
*Safety resources in the room to review
2. The redox reaction of Na and Cl2.
Viewed my video of the reaction:
Molecular and Ionic compounds/half reactions/ STABILITY
Mr. Stable/ Spontaneity
3: Daniell cell Note taking: We did not start this..
Parts of Voltaic Cell; Redox half reactions; Salt Bridge, flow of ions, flow of electrons
Voltage vs Amperage. Derivation of Energy and Voltage.
Spontaneity – Directionality of chemical reactions – based on Gibbs Free Energy
LeChatelier’s Principle as applied to Voltaic Cells
2: Reduction potentials = Overall best predictor and measure of the ability to oxidize or reduce.
Determination of net potentials
Thursday 9/5 Homework:
1. Please view the lecture below (AP Chemistry – Daniell Cell lecture) in its entirety and then complete the form below it.
2. Daniell Cell lecture Form: It will be posted this afternoon! I am making a new one!
End of THursday..
9/6 – Friday – period 2/3 – Grade 11 assembly for 20 minutes period 2
1. Lasts nights Form –
1: Voltaic Cells complete Note taking –
a) standard cell experiment/oxidizer/reducer
b) Solubility rules – Table F – started
c) Spontaneity – (Gibbs’s Free Energy) –
d) Half reactions and overall reaction (net ion reactions) – get rid of the spectators!
e) Equilibrium – Death of a chemical reaction and Spontaneity! started
f) LeChateliers Principle – How does concentration change voltage? started
2: Lab 1 – Voltaic Cell construction and begin write-up
*This Lab will just be a pencil and paper lab activity.
period 4 –
*Safety resources in the room to review – keep forgetting
1. Lasts nights Form –
1: Voltaic Cells complete Note taking –
a) standard cell experiment/oxidizer/reducer
b) Solubility rules – Table F – did not get to
c) Spontaneity – (Gibbs’s Free Energy) –
d) Half reactions and overall reaction (net ion reactions) – get rid of the spectators!
e) Equilibrium – Death of a chemical reaction and Spontaneity! did not get to
f) LeChateliers Principle – How does concentration change voltage? did not get to
*Connections: Spontaneity
In all chemical reactions there is possibility that the reverse reaction could occur. A chemical reaction that reaches equilibrium is one where the forward reaction occurs at the same rate as the reverse reaction. For example:
2NO2 (g) <=> N2O4 (g)
or
NO2 (g) + NO2 (g) <=> N2O4 (g)
Now this reaction reaches equilibrium and because the rate or speed of the forward reaction equals the rate of speed of the reverse reaction the amount of each chemical stays constant. If we were to put NO2 only in the reaction vessel and seal the container, a graph of the changes in concentration (Molarity or partial pressure) would like the following.
 |
Notice that concentration of the NO2 is large initially and decreases as the reaction proceeds. Notice the initial concentration of N2O4 is zero (it has not been made yet) and increases as the reaction proceeds. Both NO2 and N2O4 eventually level out and at this point equilibrium has been reached! If the rate of 2NO2 combining to make N2O4 (forward reaction) is as fast as rate of N2O4 decomposing into 2NO2 (reverse reaction) then the concentration of both chemicals become CONSTANT at equilibrium. |
So what does this look like? Well it is pretty boring in that it appears that nothing is going on because the reactants and products stay constant. In truth there plenty going on because forward reaction and the reverse reaction atr continuously going on but there is no NET change.
Also notice part people that the reactants (NO2 ) and products ( N2O4 ) ARE NOT Equal at equilibrium. IN this example or reaction NO2 is favored at equilibrium. Why would nature favor the NO2? Which of the 2 chemicals has the greatest dispersed energy? The 2 pieces ( NO2 ) or the larger whole (N2O4)?
The 2 smaller pieces!! Nature favors energy that spreads out.
Nature favors a pathway that has the greatest amount of dispersed energy. We call this Entropy (S)! So we know that the universe works by always providing a pathway for energy to go from a high concentrated source to a lower energy source. In other words, Chemical or physical processes can only occur if the universe provides a pathway for it to happen. This pathway is dependent upon the Entropy (S) to increase in the universe or an increase in the change of Entropy (ΔS). This is the second Law of Thermodynamics!
ΔSuniverse = increase ( IF There is a pathway!!)
That is why Heat flows to Cold always!! There are limits to what can be done with matter and it all depends on Energy dispersing! If Energy is being diluted or dispersed into the Universe then the process is SPONTANEOUS under a set of defined conditions.
If the Energy is not dispersing into the universe then there is NO PATHWAY for the reaction or process to occur!! This process is NONSPONTANEOUS under a set of defined conditions.
If you think of it this way then you can understand why a change of how fast a reaction occurs (RATE) has nothing to do with spontaneity. In the case of the reaction above 2 particles (NO2) combine to make larger one (N2O4) or 1 particle breaks into 2 particles in the reverse. This ratio is upheld no matter how many more of these multiples I have. If I have 20 pieces (NO2) I will make 10 larger one (NO2 ) and if it occurs faster by adding a catalyst then whole number ratio is upheld!
Now in getting back to the equilibrium condition in above diagram or the reaction:
2NO2 (g) <=> N2O4 (g)
The forward reaction is moving as fast as the reverse. Since there is no net change there is no increase in Entropy in the universe or there is no real preferred pathway when equilibrium is reached. At this position the Energy has been dispersed already!!! This is the death of the chemical reaction in one direction!! All reactions move in a direction to exhaust there energy into the universe until it empties! That point is equilibrium!!!!
Thus all reactions move toward equilibrium, and thus get less spontaneous over time as they approach equilibrium or reach the death of the chemical reaction! The father away a reaction is from equilibrium the more spontaneous it is!!
This diagram illustrates what I am talking about:
 At point C, there 100% NO2 and 0% N2O4 thus there is no competing reaction because there is no NO2 to combine to make the N2O4. The reverse reaction is at it maximum spontaneity and the forward reaction is at its minimum. There is a Shift in the reaction to move in the reverse. Over time its spontaneity will steadily decrease until it reaches the point of equilibrium and the “death of the reaction”. |
Notice that the equilibrium position is at the bottom!! This is where the death of the reaction or where there is ZERO Spontaneity or No more release of energy into the Universe. ΔSuniverse = O |
This shift is what we learn in Le Chateliers Principle –
Regents definition: When a stress is placed on a reaction at equilibrium, the reaction will shift forward of reverse to regain its balance.
REAL Definition: When a stress (a change in concentration) is placed on a reversible reaction the reaction will become more spontaneous in one direction in order to keep dispersing energy until it is run out (and no more work can be done). In a battery this means 0.00 volts!!
We have learned that voltage is the Energy to move current or charge around circuit either by the pushing of chemicals that spontaneously oxidize and in combination with chemicals that pull charge by spontaneously reducing. The voltage of a half reaction tells us about the spontaneity, ability to reduce or oxidize, or the pathway to do so based on the amount of dispersed energy that get released into the universe! Voltages give us a measured value of the available pathway for the redox reaction to occur.
So my question is, Why does a battery have a voltage drop? Why does it die?
Equilibrium and the death of chemical reaction is NOT unique to chemical changes only!
In physical changes (no bonds broken just attractions) equilibrium also will STOP phase changes!
That is why the melting point stays at one Temperature!
Example: Heat + H2O (s) <—> H2O (l)
Ok then can we manipulate the physical process? We do this all the time. How about placing salt on ice?
H2O (s) <—> H2O (l)
H2O (s) <—> H2O (l)
So really we limiting the reverse pathway!! Hey if we make the reverse pathway less favorable don’t we make the forward MORE FAVORABLE AND MORE SPONTANEOUS!!!
Friday 9/6 – Weekend Homework:
Please follow the order of the assignments. They are planned sequentially for a reason:
1. Make a second submission to Thursday nights Form. It will be on autograde!
There was some technical difficulties in setting – up the autograde but for those that had an original
submission you should REALLY improve your score 😉
2. Read my *Connections NOTES above.
3. Watch the Voltaic Spontaneity lecture 2017 lecture below:
3. Complete the Voltaic Spontaneity Form. It will be on autograde!
Voltaic Spontaneity Form:
4. Complete ONLY Question 1 (AP Question 2002 side)
Intro Voltaic Cells worksheet 1.pdf worksheet – This was given out earlier in the week!
( It is a Past AP problem) –
5. Review with key or the video posted below.
(Just question 1!)
Video on Intro Voltaic Cells worksheet 1.pdf :
Have an average weekend.
End of week 1!