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Archive – Q3 week 6 – 20 – 21

Week of 3/15 – 3/19 –   Remember to Refresh this page every time you open!
Please Refresh every time you open– this page is changing often!
 
The 4 day – A, B, C, D cycle looks like this:
                                                       Day                               Period
                                                                           2                       3                       4       
                
                                      In class:                          Lab                   Lab               Single Class
                                   Remote:                          Lab                   Lab               Single Class
 
                                     In class:         B          Single Class        LAB                   LAB
                                                          Remote:                     Single Class        LAB                   LAB
 
                                               In class:              C          Single Class              LAB                    LAB
                                   Remote:                     Single Class        LAB                    LAB
 
           Monday               In class:          D               Lab                   Lab              Single Class
                                   Remote:                            Lab                   Lab              Single Class
                 
 
This weeks 5 day Schedule:
 
3/15  –  Monday –  “D” Day         – period 2,3 (Lab)  –  I   2(B,D) 3(D) AP CHEMISTRY
                                                           – period 2,3 (Lab) –  R  2(B,D) 3(D) REMOTE INSTRUCTION
  
                                                         – period 4 – I  3(B) 4(B,D) AP CHEMISTRY
                                                         – period 4 – R 3(B) 4(B,D) REMOTE INSTRUCTION
 
3/16  – Tuesday –  “A” Day  – period 2,3 (Lab) –     2(A,C) 3(A)  AP CHEMISTRY
                                                           – period 2,3 (Lab) –  R   2(A,C) 3(A) REMOTE INSTRUCTION
                                                             – period 4 – I   3(C) 4(A,C) AP CHEMISTRY 
                                                             – period 4 – R  3(C) 4(A,C) REMOTE INSTRUCTION
 
3/17  – Wednesday –  “B” Day        period 2,  –  I   2(B,D) 3(D) AP CHEMISTRY
                                                            -period 2, –  R   2(B,D) 3(D) REMOTE INSTRUCTION
 
                                                            -period 3,4 (LAB) – I   3(B) 4(B,D) AP CHEMISTRY
                                                            -period 3,4 (LAB) – R  3(B) 4(B,D) REMOTE INSTRUCTION
 
3/18  –  Thursday –  “C” Day           – period 2, –  I    2(A,C) 3(A)  AP CHEMISTRY
                                                             – period 2, –  R   2(A,C) 3(A) REMOTE INSTRUCTION
                
                                                           -period 3,4 (LAB) – I.  3(C) 4(A,C) AP CHEMISTRY 
                                                           -period 3,4 (LAB) – R  3(C) 4(A,C) REMOTE INSTRUCTION
 
3/19  –  Friday –  “D” Day         – period 2,3 (Lab)  –  I   2(B,D) 3(D) AP CHEMISTRY
                                                           – period 2,3 (Lab) –  R  2(B,D) 3(D) REMOTE INSTRUCTION
  
                                                         – period 4 – I  3(B) 4(B,D) AP CHEMISTRY
                                                         – period 4 – R 3(B) 4(B,D) REMOTE INSTRUCTION

3/15  –  Monday –  “D” Day         – period 2,3 (Lab)  –  I   2(B,D) 3(D) AP CHEMISTRY
                                                            – period 2,3 (Lab) –  R  2(B,D) 3(D) REMOTE INSTRUCTION
  
                                                           – period 4 – I  3(B) 4(B,D) AP CHEMISTRY
                                                           – period 4 – R 3(B) 4(B,D) REMOTE INSTRUCTION
Sophomores are back!!!
 
ZOOM Link:
Topic: AP Chemistry 03.15 Periods 2,3,4
Time: Mar 15, 2021 08:00 AM Eastern Time (US and Canada)
Join Zoom Meeting
https://us02web.zoom.us/j/81283734474?pwd=VXU4eVhHZk4rZkc3bG84VjFNK0FDUT09
Meeting ID: 812 8373 4474
Passcode: 62nvpf
One tap mobile
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Class Notes on the limitations of the Valance Bond Theories:
 
Valence bond theories that we learned:
1: Covalent bonds – sigma, pi bonding
2: VSEPR theory – (electron orbitals repelling to form equidistance stable geometries)
3: Lewis Dot structures
4. Hybridization
 
 
Our valence bond theories = hybridization, VSEPR, Lewis dot diagrams have limitations as we have seen.  How does the chlorate ion have resonance if it is sp3 hybridized and there are no un-hybridized p orbitals to pi bond with?
 
Remember that dots on a piece of paper can give us so much information for many molecules some complex but some our rules of formal charges that help guide us to the best structure guide us to structures that actually do not exist based on their properties found experimentally!
 
Here is an example of the sulfate ion, SO4-2
 
THE LEWIS DIAGRAM BELOW REPRESENTS THE BEST LEWIS DOT STRUCTURE BASED ON FORMAL CHARGES.  Below each sulfur has a Formal charge of ZERO!
Above is what our valence bond theory predicts using the rules of Formal Charges and etc.  THIS IS NOT WHAT WE FIND experimentally!!! Actually the lewis diagrams that we find from experimental evidence looks like the following.
 
The sulfur below has a Formal Charge of +2 and yet it is the structure we identify experimentally!
 
WHAT???  How can it exist more like this structure when clearly is breaks the rules of Formal Charges (+2) on the Sulfur atom?  Actually the charge is measured to be +1.77 on the sulfur in experiments.  What gives?  The bonding is neither covalent nor ionic it is something in between.. 
 
So we are at the end or the limits of this valence bond theory. We were were always going to be limited by a theory that treats electrons as dots when we have learned from electrons exist as waves!!!
 
OK so what if we run into a Lewis Diagram that is beyond the Valence Bond Theory?
The Current AP Curriculum does not support using Formal Charges to provide guidance in building lewis dot diagrams that are beyond the Octet Rule.  The rest of the world does so we make the following rule when dealing with AP:
 
If there is a element that exists in row three and beyond then the octet rule takes preference:
Does experimental evidence support this rule completely? No.  Does experimental evidence support the use of formal charges completely? No.  We need a new theory!
 
Example:  SO4- , SO3
So lets learn a new theory that picks up where valance bond theory leaves off.  It is called MO theory or molecular orbital theory and it treats electrons as waves!
bonding 5 MO Yo!.pdf
View Download
 
bonding 5 MO Yo! complete key.pdf
View Download
 
Selected correlation graphs (Li2 – C2) – These were in the student presentation “MO Bonding “
bonding 5a MO Yo classwork!.pdf
View Download
 
Used this worksheet after the “MO Bondng”
bonding 5 MO Yo! oxygen and nitrogen.pdf
View Download
 
MO – N2 vs N2+.pdf
View Download
 
MO orbital Theory Presentation:

MO Conjugated Theory

 
3/15  –  Monday –  “D” Day – Homework – 
1. Complete the Bonding Test 2 and Return it in person tomorrow.
2:  Watch the Lecture below on MO (molecular orbital theory) . You are going back to MIT! You will only need about the first 30 minute of the video.
3.  Complete the form below:
 

MO Theory Form 2021

End of Monday..

3/16  – Tuesday –  “A” Day  – period 2,3 (Lab) –     2(A,C) 3(A)  AP CHEMISTRY
                                                     – period 2,3 (Lab) –  R   2(A,C) 3(A) REMOTE INSTRUCTION
                                                     – period 4 – I   3(C) 4(A,C) AP CHEMISTRY 
                                                     – period 4 – R  3(C) 4(A,C) REMOTE INSTRUCTION
 
Zoom Link:
Topic: AP Chemistry – periods 2,3,4
Time: Mar 16, 2021 07:00 AM Eastern Time (US and Canada)
 
Join Zoom Meeting
https://us02web.zoom.us/j/81840235019?pwd=eUlpSkY4WjZIOU9md0NqY3RCckJzQT09
 
Meeting ID: 818 4023 5019
Passcode: P5u2AV
One tap mobile
+16465588656,,81840235019#,,,,*488591# US (New York)
 
Period 2, 4:
 
1. Homework Review of the MO Theory Form:
 
MO Theory Form 1920 – Key p.pdf
View Download
2.  Types of Solids through presentation: Whatever theory.
 
        Gap theory –   Size of gaps between electron energy levels that explain electrical conductivity
                                    or the lack (large gaps) AND absorption of light (pigments).
 
        Pi stacking = delocalization that allow delocalization of electrons through metallic 
                                  and SOME molecular compounds. Creates smaller gaps between energy levels.
 
        network solids  – molecular compound with a continuous crystal
 
        Diamond vs Graphite – type of network solids that have differ based on pi stacking
 
        chromophores – molecular compounds that have delocalization that are pigments.
 
         crystal field theory –   remember me?

MO Conjugated Theory

 
Types of Solids.pdf
View Download
 
Types of Solids key.pdf
View Download
                                                                                                                            NEW!
 Ionic Solids Molecular solids     Network solids   Metallic Solids
 crystals of ions Molecules!!! crystals of covalent bonds crystals of nuclei in a sea of mobile electrons
Ex:  NaCl, NaNO3, NH4Cl Ex: H2O, CH4, C6H12O6     Ex: SiO2, C (s)graphite   Ex: Ni, Cu, Any metal element
 continuous ionic bonds    IMF depending on polarity   continuous covalent bonds              metallic bonds
 Chromophores – pi stacking if conjugated

  Non Chromophore  –

  Crystal field splitting
 Conductive if in (l) or (aq)   Non conductive      *Non conductive            Conductive
   high melting points  
     breaking ionic bonds
   Low Melting points
breaking IMF not Bonds!  
   high melting points
 breaking covalent bonds
   high melting points
   breaking metallic bonds
Network solids are the RARE CASE when some molecular compounds make continuous covalent bonds in their crystals.  Diamond and Graphite are examples.  Most molecular solids are held by IMF*Graphite is the only Network solid that conducts due to the delocalization of electrons throughout its crystal.
 
IMF = Intermolecular Forces – ATTRACTIVE forces that hold molecules together
 
Molecular solids have the lowest melting points because when you give them heat you are separating molecules HELD TOGETHER BY ATTRACTIVE FORCES (IMF) that are only a fraction of the BOND Energy of Covalent, Ionic, or Metallic BONDs!  It takes less energy to separate molecules held together by attractive forces than it does to separate atoms or ions (breaking bonds).
 
Since we are breaking only attractive forces AND NOT BONDS heating this solid would be a PHYSICAL Change as the chemical formulas (of the individual molecules) would not change!
 
All phase changes (ex. melting, freezing) of molecular compounds are always physical changes!!!!
 
                                                H2O (s)  —-> H2O (l)  —-> H2O (g) 
 
                                                               Ice     —->  water    —->  steam
 
We are only separating the attractive forces between the molecules and thus the chemical formula does not change.
 
In our copper Iodine lab earlier in the year why did the Iodine sublime?
                                                                        I2 (s)  ——>   I2 (g) 
 
Because Iodine is a molecular solid with a low melting (sublimation) point due to the weak attractive keeping iodine as a solid.
Period 3 – Intermolecular Forces – (IMF’s) lesson begins using presentation in homework.
 
Intermolecular Attractions Presentation:
Why can liquid nitrogen cause oxygen gas to condense into a liquid?
 
The making of liquid oxygen:
 
3/16  – Tuesday –  “A” Day – Homework 
 
1. Complete the Types of Solids.pdf worksheet and review with the key.
 
Types of Solids.pdf
View Download
 
Types of Solids key.pdf
View Download
 
2.  View the Lecture on the Intermolecular Forces (IMF’s) below.
      Remember that these forces are the forces that keep molecules together as a solid or liquid. They are are also the forces that make gases deviate from Ideal Gas behavior.  They are also are the reason each compound as a liquid has a unique vapor pressure and boiling point.
 
3. Complete the Form below on identification of the IMF’s in the molecules below:
 
 
4. Please complete the AP Survey.
 
Lecture on intermolecular attractions (started or completed in class):
START at 19:00 (we LDF’s in class).
Intermolecular attractions form:
This form is on auto-reply and you have 3 submissions that are due by tomorrow morning.
 

Intermolecular Attractions Form 2021

AP Survey Form:

AP Test Survey

End of Tuesday..

3/17  – Wednesday –  “B” Day        period 2,  –  I   2(B,D) 3(D) AP CHEMISTRY
                                                                 -period 2, –  R   2(B,D) 3(D) REMOTE INSTRUCTION
 
                                                            -period 3,4 (LAB) – I   3(B) 4(B,D) AP CHEMISTRY
                                                            -period 3,4 (LAB) – R  3(B) 4(B,D) REMOTE INSTRUCTION
Zoom Link:
Topic: AP Chemistry – 03.17 Periods 2,3,4
Time: Mar 17, 2021 08:00 AM Eastern Time (US and Canada)
Join Zoom Meeting
https://us02web.zoom.us/j/82425650588?pwd=emVTNmFiRzYyYmZaMHUxL0orak1CUT09
Meeting ID: 824 2565 0588
Passcode: u5ZvvE
One tap mobile
+16465588656,,82425650588#,,,,*400363# US (New York)
                                                                                                                        NEW!
 Ionic Solids Molecular solids     Network solids   Metallic Solids
 crystals of ions Molecules!!! crystals of covalent bonds crystals of nuclei in a sea of mobile electrons
Ex:  NaCl, NaNO3, NH4Cl Ex: H2O, CH4, C6H12O6     Ex: SiO2, C (s)graphite   Ex: Ni, Cu, Any metal element
 continuous ionic bonds    IMF depending on polarity   continuous covalent bonds              metallic bonds
 Chromophores – pi stacking if conjugated

  Non Chromophore  –

  Crystal field splitting
 Conductive if in (l) or (aq)   Non conductive      *Non conductive            Conductive
   high melting points  
     breaking ionic bonds
   Low Melting points
breaking IMF not Bonds!  
   high melting points
 breaking covalent bonds
   high melting points
   breaking metallic bonds
Network solids are the RARE CASE when some molecular compounds make continuous covalent bonds in their crystals.  Diamond and Graphite are examples.  Most molecular solids are held by IMF*Graphite is the only Network solid that conducts due to the delocalization of electrons throughout its crystal.
Period 2, 4:
 
1. Types of Solids Review – 
 
Types of Solids Key New 1718 p.pdf
View Download
2. Review of last nights form- 
 
Intermolecular Attractions Form 1920 – Key pp.pdf
View Download
– dipole – dipole, H-Bonding Review – 
 
– Review the concept of solubility/miscibility with water
 
The making of liquid oxygen:
 
Sucrose: 
 
3.  Cross – Linked polymer activity – 
 
Why would N2 (l) be a great
 liquid to use to create a large amount of vapor pressure?
 
Period 3:  MO theory to Gap to Chromophores and network solids

MO Conjugated Theory


Slime (Cross-Linked Polymer)? 
 The long strands of the top and bottom molecules are held by the middle molecule attracting them. Notice the dashed lines in between the three molecules shown that represent the attractive forces.  Each different molecule is circled. These dashed lines are Intermolecular Forces (IMF’s) that are keeping this SLIME together as a solid.  They are written as dashed lines so not to confuse them with bonds. Because this solid is held by IMF which are much weaker than bonds you can imagine that it would not take much heat to “melt” your Slime. It would have a very low melting point.
 
3/17  – Wednesday –  “B” Day  – Homework  RAT QUIZ Tomorrow on MO, Gap theory, and IMF
*Please pay attention for your homework instructions by class!
1: Complete the IMF comparison worksheet 1819.pdf worksheet using the 
      Lecture below for the worksheet.  The key is available for your viewing pleasures.
      The key is helpful but the lecture is more important!
 
IMF comparison worksheet 1819.pdf
View Download
IMF comparison worksheet 1819 KEY.pdf
View Download
IMF Comparison Review –  Lecture:
2. Complete the IMF comparison 2 worksheet.pdf for more practice on IMF’s
      with the key or the video below it.
 
IMF comparison 2 worksheet.pdf
View Download
IMF comparison 2 worksheet Key.pdf
View Download
IMF comparison 2 worksheet.pdf lecture:  
This was a lecture made with the older version of the worksheet that you have.
 I updated your worksheet to show the actual structural formulas.
 
End of Wednesday..

3/18  –  Thursday –  “C” Day     – period 2, –  I    2(A,C) 3(A)  AP CHEMISTRY
                                                           – period 2, –  R   2(A,C) 3(A) REMOTE INSTRUCTION
                
                                                           -period 3,4 (LAB) – I.  3(C) 4(A,C) AP CHEMISTRY 
                                                           -period 3,4 (LAB) – R  3(C) 4(A,C) REMOTE INSTRUCTION
 
Zoom link:
Topic: AP Chemistry – 03.18 Periods 2,3,4
Time: Mar 18, 2021 08:00 AM Eastern Time (US and Canada)
Join Zoom Meeting
https://us02web.zoom.us/j/84714497480?pwd=YUpKMmRJNUovTm4zM1ZQT0o0SXE1Zz09
Meeting ID: 847 1449 7480
Passcode: 6jrbf0
One tap mobile
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Period 2,3:
 
1. Quick review of Homework worksheets:
 
IMF comparison worksheet 1819 KEY.pdf
View Download
 
IMF comparison 2 worksheet Key.pdf
View Download
 
2. IMF RAT QUIZ- 
Period 4:  Lab 21? – TLC of Universal indicator

 

 
3/18  –  Thursday –  “C” Day – Homework – 
 
1.  TLC (Thin Layer Chromatography) Lab background and Hypothesis writing.
 
READ BELOW!!!!
 
This is our last formal lab this year.  I would like for you to write a background on how TLC works and relative strength of the different IMF’s in the molecular compounds (chemical indicators) that make up a industry standard mixture called Universal Indicator.
 
Universal Indicator Acid/Base Indicator that has a unique color for each pH value:
 
 

A lot of pool kits that measure pH use Universal Indicator!
Universal Indicator can accomplish this broad range of colors because it is a homogeneous solution of three Acid/base indicators (CHROMOPHORES!!!!!!!!!!!!) that change their amount of conjugation based on the concentration of available protons (H+) or hydroxides (OH).
 
Also do not forget the acid/base indicators ARE CONJUGATE ACID and CONJUGATE BASE solutions which are Buffer solutions.
 
                                              HIn                             —->                            H+       +         In
 
                                         Conjugate Acid                                                                                      Conjugate Base
                                              one color                                                                                                 New color
 
  Phenolphthalein is an example:
There are slightly different types of Universal Indicators that use slightly different mixtures of indicators. We will using the BOGEN Universal Indicator mixture.
 
Bogen Universal Indicator Mixture:             1.   Methyl Red                      pKa = 4.95
                                                                                         2.  Bromothymol Blue         pKa = 7.1
                                                                                         3.  Phenolphthalein             pKa = 9.4
 
So the colors of each pH from above are due to the mixture colors of each indicator at a certain pH levels:
                                                                                                 (negative theory of light)
 
Okay so the point of this lab it separate each of these 3 individual molecular substances by using TLC (Thin Layer Chromatography).  Thin Layer Chromatography is another physical way we can separate mixtures. 
 
– We have separated homogenous mixtures before using evaporation in the carbonate lab where we added HCl to an unknown white powder (that was either NaHCO3 or Na2CO3) and created NaCl (aq) and CO2 that left as bubbles.  We boiled off the water (separated the H-Bonds of water) and obtained dry NaCl (s) which we used by stiochiometry to determine our unknown. Connections!!!!
 
– we also studied distillation (of Coca-Cola) as another physical separation technique of mixtures!
 
– we also used filtration of a precipitate to separate a mixture in our gravimetric titrations!
 
Remember that solutions are mixtures that are soluble that are held together by IMF’s!  When we separate a mixture it is a physical change because we are not breaking bonds we are ONLY BREAKING IMF’s between MOLECULES!!!
 
TLC just like all chromatography separates a mixtures based on the idea that in a mixture the individual molecules retain thier individual properties since their chemical formulas are not changing in the process.  This means that each chemical indicator will retain their individual solubilities (their percentage of non-polarity due to the amount of predominant LDF forces or their percentage of polar nature due to the amount of dipolar and H-boding) in the mixture. 
 
Thus in TLC we will separate the 3 acid/base indicators by their solubility to either a mostly non- polar solvent (mobile phase – hexanes) or polar solvent (stationary phase – Silica Gel).  
 
We will spot a TLC plate with Universal Indicator in a starting position close to the bottom of a Silica TLC plate (stationary polar phase) and add a liquid solvent – hexanes (non-polar mobil phase) that move up the Silica TLC plate by capillary action.  When the solvent reaches the “spot” or mixture EACH component of the mixture, 
Methyl RedBromothymol Blue, and Phenolphthalein will have a choice to either stay with the polar Silica Gel on the TLC plate or move with the non-polar mobil hexanes.  BASED on their individual molecular structures (that define the IMF’s that they have), each chemical indicator will have a unique amount of polar or non-polar characteristics AND they will each move a unique distance up the TLC plate.
 
– If one of the chemicals is more polar (have stronger dipolar forces or have H-bonding) than the other three than they will prefer the Silica TLC plate and MOVE LESS than the other chemical indicators of the mixture that must have more non-polar characteristics.  
 
– The chemical indicator that is the most non-polar (have mostly LDF’s with less dipolar forces), would prefer to be attracted to the mobile non-polar hexane solvent and thus move up the plate more.
 
*Remember this a separatory technique based on solubility. Solubility is based on how similar the IMF’s have with the mobile non-polar solvent (hexane) or the polar stationary solvent (TLC silica Plate). Look at the two solvent molecular structure above to identify what IMF are most similar with each solvent! 
 
The distance that the individual chemical indicators move compared to the original spot will be measured.  
 
Tonight you will accomplish 2 things:
 
1.  Write a background on the TLC of Universal Indicator Lab.  
        This will be our last formal lab write – up.  You will have an email with the link to your shared doc to begin this lab.  The focus of your background MUST include a comparison of the polarity and non-polarity of the three chemical indicators in Universal Indicator.  This comparison must include a discussion of the IMF’s of the three chemicals using diagrams of their molecular structures.  Thus your background must include molecular structure that you should search for and place in your background. The whole purpose of the background is to develop a your argument or your position on whether which chemical indicator is the most polar and non-polar. 
 
2.  Write a Hypothesis based on your position established in your background.
        Basic Format: If the independent variable does this the dependent variable will do that .
 
           The Dependent Variable is the distance the indicator moves up the TLC plate.
 
                            We will measure that distance by a calculation called Rate of Flow = Rf
 
For those that had me last year in AP Biology we separated the different pigments in the photosystems in the chloroplasts in spinach leaves.  We were able to separate three different pigments (CHROMOPHORES!!!!!!!)  in that lab.
 
Yellow layer – Carotenoids – 
 
 
Green layers – Chlorophyll A and Chlorophyll B – is one slightly more polar?
 
– Notice these pigments are chromophores!!!
 
– There were three layers separated in the Time Lapse Chromatography below.  Looking at the pigments separate in the video below, and the molecular structure above can you identify the chemicals in the chromatograph? Why was the yellow layer almost at the top while the 2 green layers barely moved at all?
– Also notice that we did not spot this TLC plate, we rolled a coin on a spinach leaf unto the TLC plate to make line. The green line was our starting point.
So the assignment is to rank the polarity and non-polarity of the three chemicals in the mixture of Universal Indicator based on what you know of IMF’s AND Predict which chemicals will travel the greatest distance up the TLC plate and which chemicals with travel the shortest distance.  This discussion is the subject of your Background of the lab. Use these structural formulas in your Background.
THEN Write a hypothesis based on your background.
Hypothesis Example: Chemical A will have the largest Rate of Flow (move the farthest on the TLC plate) while the Chemical B will have the smallest Rate of flow.
Bogen Universal Indicator Mixture:             1.   Methyl Red                      pKa = 4.95
                                                                                         2.  Bromothymol Blue         pKa = 7.1
                                                                                         3.  Phenolphthalein             pKa = 9.4
 
Methyl red:
Bromothymol Blue:
 
Phenolphthalein:
 

 

Acid Base Indicators

End of Thursday..

3/19  –  Friday –  “D” Day         – period 2,3 (Lab)  –  I   2(B,D) 3(D) AP CHEMISTRY
                                                         – period 2,3 (Lab) –  R  2(B,D) 3(D) REMOTE INSTRUCTION
  
                                                         – period 4 – I  3(B) 4(B,D) AP CHEMISTRY
                                                         – period 4 – R 3(B) 4(B,D) REMOTE INSTRUCTION
 
Zoom Link:
Topic: AP Chemistry – 03.19 – Periods 2,3,4
Time: Mar 19, 2021 08:00 AM Eastern Time (US and Canada)
Join Zoom Meeting
https://us02web.zoom.us/j/81901646062?pwd=TWdvVmVRTWlkYWJXczZmT0NBQlY2Zz09
Meeting ID: 819 0164 6062
Passcode: mj6UVj
One tap mobile
+16465588656,,81901646062#,,,,*366323# US (New York)
 
– phase diagram of water and carbon dioxide:
 
1. Discussion of universal indicator, ph, Chromatography, AP Biology pigment lab
 
– making of dry – Ice – deposition – JOULE-THompson effect – IMF’s!!!!!
 
2: CO2 Demo – Universal solution and dry ice:
        warm water and Universal (green) plus few drops of .1 M NaOH solution- add solid CO2
        on overhead projector with light hole (from sunset demo)
 
3. TLC (Chromatography) of Universal Indicator Lab
 
TLC of Universal Indicator p.pdf
View Download
                             
Presentation used for discussion:
FULL REMOTE STUDENTS:
Here is a look at the time lapse of what students saw today in the TLC lab:
Remote students use the image posted belowuse for the data collection in your lab:
 

 

3/19  –  Friday –  “D” Day  – Homework:

 
TLC Lab write- up – Data gathering and calculaltions
 
1.  Please download Logger Pro from SELF – SERVICE when you are still in school.
 
2.  Make sure everyone has the picture of the chromatograph that I sprayed with a base to expose          the phenolphthalein spot.
 
From a lab group today:
 

 

*Notice that the phenolphthalein trails the methyl red.  It is probably faint in your picture but it is there.

They do not use a lot of it in the Bogen Universal indicator mixture and thus it is not a concentrated spot.
 
Our next step is to calculate the RATE of Flow for each SPOT .
 
RATE of Flow = R = distance each spot traveled from the starting position (bottom line)
                                                                  distance to solvent font (see diagram)
 
WE Need to measure these spots and we will do so WITH the pictures of your labs chromatograph and LOGGER PRO.
 
1. Make sure you have downloaded Logger Pro in school today.
2. Open Logger pro.
3. Click on InsertPicturePicture with photo analysis
 
4. Find your picture of your chromatograph in your computer and click open.
 
5. Your picture will appear. If it is too big or small just click the upper right corner of the image to resize so that you can see the entire image.
 
6.  Click on the set scale button on the right of the image.  The 4th button down. The one that is darkened.
7. When you click the set the scale button a cross appears. Please click and drag with that cross from the top of your chromatograph to the bottom. WE are setting the computer scale so that it will be able to measure.  Everyones TLC plate is 75 millimeters (mm) as I illustrated in the diagram above. Once you drop and drag the cross the exact length of the TLC plate ADD 75 for the distance and mm for the unit in the pop-up box.
Then click Ok to close the pop-up box.
 

   

8. Now we are ready for the computer to measure for us.  Please click on the 5th button down, the photo distance button and the cross appears.  Click and drag with the cross from the starting position to the middle of one of your dots.  I did the methyl red of the last group. The program will give you a value in mm for that distance. Make sure that you click and drag with the cross from exactly from the starting point to the middle of the dots. Record each distance and measure all of your spots this way.
-Also measure the Distance to the solvent front – Thank You Rose H.
 
9. Calculate the Rate of Flow for all 9 dots. Use page three of your handout portion of your lab to organize you data.  Please average your Rate of flow for each indicator in the mixture.
 
*Also identify each spot from your image of the chromatograph as I did in the illustration above.
 
10. Place data tables, images, into your Data section of your lab.
 
11.  Complete your Procedure, Data, and Results and Conclusion section in the shared doc that I sent you today.
 
 
    
End of Week 6!