Select Page

Archive – Q3 week 9 – 20 – 21

Week of 3/30 – 4/3 – Please Refresh!

 

3/30 –  Monday –   *9:30 am Meeting to review homework
 
                                  10:00 am Rate Law Free Response Test – 
 
Link to today’s Meeting (first 30 minutes I reviewed the weekend’s concept):
*You could watch me review the homework below:
Reviewing the weekends homework:
 
1: Review of mechanisms that determine Rate Law.
    Really just took questions on the homework and worked on the 2nd (middle question) of the packet for review        for the Rate Law/ Ksp Part 2 TEST 🙂
 
2: Mechanisms that determine rate Law – Fast equilibrium
                           
3/30- H0mework:  – Integrated Rate Law Formulas
 
 Please follow these instructions. If you do these out of order you will not learn an reinforce the concepts that I want you to review.
 
 I am asking a lot here but this is studying for the AP in the best way that leads to the best results!
 
– Also Wednesday this week you will be taking a 40 minute part 2 (2 question test) that will be a RATE LAW and KSP Part 2 question.  Please review your KSP tests also look at Wedneday this week and you will find a class lecture of me reviewing a couple of past released part 2 Ksp questions.
 
1:  Please watch the Monday nights’ Lecture below on the derivation of the 0th, 1st, and 2nd Order Integrated  Rate Law formula. 
 These formulas help us utilize time with changes in our reactant concentrations!  
These formulas are integrated formulas (Calculus) and they are needed to link “real time” with actual concentrations (area under curve).  Remember that Rate Law is the Rate from INITIAL CONCENTRATIONS of reactants. That Rate that we have been calculating for changes the instant the chemical reaction starts so it really becomes useless AFTER some time period after time zero.  They utilize concepts of derivative and integrals which many of you have NOT had in math YET! You do not need to use these concepts to answer the following questions, just the formulas:
 
How long does it take for the reaction to be completed?
How long does it take for the concentration of my reactant to reach a certain value?
Given the time, how much of the reactant remains?
What is the shelf life of the chemical? (how long does it take to decompose?)
 
2. Read the notes on the new INTEGRATED RATE LAW Formulas – Skill 8 and Skill 9
 
3: Complete the Form that goes along the video (this will be in auto-reply)
*4: Complete the following worksheet and review with the keys: 
Give yourself 40 minutes, these are 2 part 2 questions, then grade. The goal is 7 out of 10.
 

2005B 2009 Kinetics quiz 2013 with college board and grodski keys.pdf

 
These formulas are USED WITH TIME!! They are used 2 ways.
 
1: They can be used to identify the Rate Order By how they are graphed. For instance if you graph a 1st order reaction using the ln[A]t  (ln of concentration of reactant at some time period) in the y axis and the t (time)  in the x axis it will be linear with a negative slope.  If it is not linear with a negative slope then the reactant is not 1st order.
See the reference table below.
2: Once you identify the whether the RATE ORDER is 1 or 2 use the correct integrated rate law equation to solve either the time (t), initial concentration [A]0 , concentration of reactant after some time[A]t ,
or the rate constant, k.
What this lecture describes is the mathematics  (Calculus ) needed to solve for or Link Time with remaining reactants.  These important derivations will derive our Integrated Rate Law Formulas that are given to us in our reference tables.   They help us identify the order (or exponents) of our reactants in our Rate Law Equation just by graphing the changes of concentrations of the reactants in time during a chemical reaction.   
 
Here they are in our reference tables:

It is usually very helpful to utilize these equations when you arrange them into a linear equation.

  1st Order:                   X   –>  Y  
 
                                    R = K [X]1    
                                
                             ln[A]t – ln[A]0 =  -kt
 
                             ln[A]t  =   -kt   +    ln[A]0
                                y      =    mx  +      b
                                        (negative slope)

 

 2nd Order:                X  +   X  –>  X2
 
                                           –       =  kt
                                 [A]t    [A]0
 
                                             =  kt   +    1
                                 [A]t                [A]0   
 
                                           y     = mx  +   B
                                                                               (positive slope)
 
 
 

 

Monday Night’s Lecture:
 
Chemistry Calculus Presentation that I used in the lecture above.

Chemistry Calculus

 

Monday Night’s form:

 
Chemistry Calculus Basics in a screencast lecture: 
This was part of the Monday nights lecture.
Derivation of the Integrated Rate Law formulas in a screencast lecture.
This was part of the Monday nights lecture.
End of Monday….

3/31 – Tuesday –  We will meet at 10:00 am. –Please disable hardware acceleration in Chrome as per my email yesterday to improve the Zoom performance.
 
Link to today’s Recorded lecture: 
 
– Tomorrow we will have a RATE LAW and KSP 45 minute Free Response test.
   I have some Ksp Review lectures below. (Why does Ksp seem so long ago?)
 
 
Class Lecture of the review of Integrated Rate law Equations and your homework:
1. Review Lecture on Integrated Formulas/concepts – video posted above
2. Crystal Violet and OH- Kinetics Lab.
        Determine the order with respect to [CV] using graphs.
                              
Kinetics 2 – rate law KEYp .pdf
View Download
                                                              
Reference Table:

This is the first order integrated formula.

This is the second order integrated formula.

There is no zero order integrated formulas on the AP.

This is the Arrhenius equation that ties activation energy ( Ea) and temperature to the rate law constant. 

Spectrophotometry

Crystal Violet: Chromophore – Conjugated molecular compound
 
3/31 – Tuesday Homework: 
1:  Please complete Kinetics 1 worksheet (side 2) and review with key
2:  Please complete Kinetics 2 worksheet (1st worksheet 1984B, question c and d)
      and review with the key.
3.  Kinetics Lab is due tomorrow/ You may have completed in class- There is nothing for you to do with this. We did this as a virtual demo lab.
     
4. Complete a 5 question MC form on rate law
5:  REdo 2005B question on Mondays Homework:
 

2005B 2009 Kinetics quiz 2013 with college board and grodski keys.pdf

I have a video below (INTEGRATED CALCULATIONS LECTURE) that review the question with the integrated rate law questions.
Catalysts and Activation Energy (Ea = Activation Energy)
The Arrhenius equation calculations are not on the AP but the concepts of how the k (Rate law Constant, like the equilibrium constant) is related to temperature.
 
5.  Please watch the Lecture on the derivation of the half – life formulas and lecture on the 
     Activation Energy, Ea.
6. Complete the form below that is based on the 2 lectures.
Kinetics 1 – rate law.pdf
View Download
 
Kinetics 1 – rate law key.pdf
Kinetics 2 – rate law.pdf
View Download
Kinetics 2 – rate law KEYp .pdf
View Download
Rate Law Multiple Choice Form:
Derivation of half – life formulas:

             

Activation Energy Lecture:

Half Life Activation Energy (Ea) Form:
INTEGRATED CALCULATIONS LECTURE – 2005 HW rate Law problem reviewed:
KSP REVIEW of 2 AP Free response Problems (today after school) – 
Rate LAW presentation:

Rate Law

 

RATE LAW Lab requirements: YOU MAY HAND THIS AS LAB GROUP or individually –Not this year:(
 
1: Title : Graphical Analysis of the reaction of CV and hydroxide
2: Objective; To determne the order of reaction with respect with CV.
3: Data:
 
Showing off – determining the half life will identify the order of the reaction.
 
    a) I need 3 graphs. One that is the original vs time. This the one you did in class.
    
    b) Second and Third = the other is either 1/[CV] vs time or ln[CV] vs time
        Whichever is linear.  You will need to make 2 graphs. Pick the data points from the original       

         graph, one every 10 seconds (out of the total 200 seconds of data collected and convert to 

1/[CV]  
         or 
ln[CV]. Remember that absorbance is
 proportional to 
Molarity. 

Use Logger Pro to generate a new  

         graphs from scratch. Go in order when you do so.  The graph that gives you a linear line will tell you           what order is.
    c) Please write the Rate Law R = k [CV]m[OH]0 based on your graphs!
    
    d) Make a statement about how you determined the order with respect with to [CV].

    e) Remember that the OH- does not significantly change because it is about 1000x greater in Molarity            

than the CV THus it is staying relatively constant!
 
    f) Calculate or determine the rate law constant (k) with units.
 

Initial concentrations:  [CV]: 2.5 x 10-5 M  and 

[OH-]: 0.1 M
                                     1.5 ml of 

[CV] and 1.5 ml of 

0.1 M of OH–  in cuvette.
 
Today’s Logger Pro Class Files for the above lab:

End of Tuesday..

4/1 – Wednesday – We will meet at 9:30 to review the concepts from last night.
                                     At 10:00 in the same meeting we will take the 
                                     Free Response Test (20 point – Rate Law and Ksp).
 
Last nights forms keys:
Rate Law Multiple Choice Form:
 
Half-Life Form:
 
1.  40 minute – part 2 question test – 1 Ksp and 1 Rate Law part 2 question. (40 minutes)
                                                              
4/1 – Wednesday Homework: Acid Base Basics* 
 
*Now I know that AP Central has posted that they are deemphasizing the acid/base concepts from the AP test this year but from my experience with “NEW” versions of AP tests, AP Central does not always do what they say.  They have in multiple occasions gave questions on tests that seemed out of the “New” Curriculum.  Your AP test this year is truncated and with that each question will be weighted more.  In the event that an acid/base concept appears I want you to be ready.  The game here is that your AP grade is based on how well you do against the other students in the nation.  Finishing the acid/base unit will possibly give you an advantage and besides that you need this topic for college chemistry. WE DID MOST OF THIS UNIT IN NOVEMBER so all we have left is the equilibrium (ICE tables) part of the unit.
 
Today’s Test Reviewed:
 
1. review the test with video that will be posted or keys through REmind:
 
2. Watch the Acid/Base Basic lecture 1 – THIS IS REVIEW!!!!!
 
 I will be directing you to the Acid and Bases Intro packet Key p.pdf where needed in the form.
 
3.  Watch the Acid/Base Basics Lecture 2 – New (equilibrium)
4.  Complete the Form.
  We did the Acid and Bases Intro packet in November! You may want to look through the key of this packet to help stir the acid/base knowledge. 
 
 I will be directing you to the Acid and Bases Intro packet Key p.pdf where needed in the form.
Acid and Bases Intro packet new.pdf
View Download 
 Acid Base 2 – Ph Ka.pdf
View Download
Acid and Bases Intro packet Key p.pdf
 Acid Base 2 – Ph Ka key.pdf
View Download

feeling spacey.. 

Acid Base 1a – Table of Acid and Base Strength.pdf
Today’s Test Reviewed:
Acid Base Basics – 
 
Acid/Base Basic lecture 1
 

Acid/Base Basics Lecture 2 

 
 
Screencast lecture of acid/base basics 1:
Lecture for Acid Base 2 – Ph Ka.pdf worksheet, which would help for the last 2 questions in the above form.
 
ACID BASE Basics 1 and 2 Form:
End of Wednesday..

4/2 – Thursday – We will meet today at 10:00 am.

Link to today’s recorded meeting: 
 
1.  KSP/rate law Test Rate Law Review
 
2.  Keq, Ka, Kb and the multiplication of Equilibrium constants: Form review last week
 
3, Acid Base basics – Important acid base skills needed -THIS IS A REVIEW!!! WE did this in November!!
This was part of your homework:
 
        A) Auto Ionization of water:              H2O  <->  H+  +   OH
                                                                    H2O + H2O  <-> H3O+  +  OH
 
        B) Acid Base Definitions (Arrhenius,  Bronsted Lowry,  Lewis)
        C) pH and pOH determination, Kw = [H+/H3O+] [OH] = 1 x 10-14
        D) pKw =pH  + pOH
        E) Kw = Ka x Kb  or pKw = pKa  +  pKb
       F) Strength of Acids = Ka – acid dissociation constant (equilibrium constant for acid conjugate base equilibria)
       G) Strong Bases
Classwork:  I will do this below in the meeting today..
 
1. Note taking on 2 titrations (that we did in November!) – 5 points
 
Titration curves revisited:
Strong Acid/Base Titration Review:
2. Please view the 2 Titrations videos below.  
 What I tried to accomplish today was to demonstrate where Equilibrium problems appear in Acid/Base titrations.  We covered all of acid and base in November but I left out the equilibrium like Point 1 and 4 of the titration curves.  SO I demonstrated the verification of point 1 and point 4 in the second titration.
All calculations of all the points in the titration graph are available in the Acid Base Notes in the 3rd quarter.
    a) Strong Acid ,  Strong Base – No equilibrium here
25.0 ml of HCl is titrated with 0.10 M NaOH. 2.8 second = 1 ml of base added.
                HCl (aq)   +   NaOH(aq)  —> NaCl (aq)  +   HOH (l)
 
                 H+(aq)  +   OH (aq)   —-> HOH (l)
    b) Weak Acid, Strong Base – Equilibrium is need to complete the points we did not complete in                                                                 November.
25.0 ml of acetic acid is titrated with 0.10 M NaOH. 2.8 seconds = 1 ml of base added.
           
         HC2H3O2      +       OH      —–>    _________   +   H2O
             ?M, 25 ml              0.10M
Titration curves revisited for notes:
Strong Acid/Base Titration Review:

 

Weak Acid/ Strong Base Titration Review:
4/2 – Thursday – Homework: 
 
 
1. Please complete the Acid Base 8 – Titrations.pdf  worksheet and review with the key.
 
I reviewed point 1 and 4 in class today (that were equilibrium based).  In you want further instruction please view the lectures on the titrations below.  Also every point is available for review in the Acid/Base Notes page/
Acid Base 8 – Titrations.pdf
View Download
 
Acid Base 8 – Titrations Key p.pdf
View Download
Weak Acid /Strong Base Note Taking Lecture: (optional please!)
You may need to view explanation for points 3 and 4 in the  to complete the back page of the homework. If cannot get to the whole video thats ok but please get to points 3 and 4 (35:57)!
Strong Acid /Strong Base Note Taking Lecture: Optional Fun!
                                      
End of THURSDAY..

4/3 – Friday – We will meet today at 10:00 am. 
                         Extra Help will be the 1st 10 minutes of each daily zoom meeting or in private email.
 
Link to today’s recorded lectures:
 
*Monday 4/4 will be updated today sometime as I have to post only on Friday’s and Tuesday’s as per the district online plam
1. Today I sent out a google doc for the completion of the Ammonium Chloride Lab. That doc had the link to the       Titration curve collected in the video below.
 
In this virtual titration you need to convert the volume from seconds. The buret had a rate of flow that was 2.8 seconds per milliliter (1 ml = 2.8 seconds)
  
Today’s virtual titration:
TODAY’s TITRATION – 
NH4Cl  titration with strong base (0.10 M NaOH)
 
         25.0 ml NH4Cl titrated with 0.10 M NaOH
4/3 – Weekend Homework:  AP Chemistry Exam Date – MAY 14th at 2:00 pm
 
1.  Complete the Ammonium Chloride Lab. I will post a video on how to verify the points 1 – 5.
      Please complete the calculations On Your Piece of Paper and upload the image to the appropriate 
      box for each point.
 
– Due Monday!
 
    – If you need help with calculating these points please: 
 
                a) use the Lecture below to help you with these points (most of these points are review!)
                b) Use my notes in quarter 3 – Acid base Titration notes  I have each point reviewed.
      
       – Tuesday next week, we will have a Titration Curve test just like this Lab where you will verify all 5 points with  
         calculations. I originally had this posted as a Free Response Test but changed it due to test date NOW being in May           again.  
 
Please identify the following from the Titration curve of the NH4Cl
            A) Net ion Reaction for the Titration (Driven)
 
            B) Net ion reaction for the NH4Cl in water.
 
            C) Calculation that determines the concentration of the NH4Cl
 
            D) Calculate the Ka of the acid.
 
            E) Verify the following 5 points on the Titration curve:
 
                    1) initial pH (in side the beaker BEFORE IT IS titrated) – pH at zero volume.
                    2) Half equivalence point  – volume and pH
                    3) a point in the buffer region  USE the 30 sec mark!
                    4) Equivalence point – Volume and pH
                    5) Final pH – pH at the End of titration
 
2.  Complete Thursday nights homework again as it will make more sense AFTER 
      completing the Lab. IF you can identify which point you are solving for on a titration curve for these  
      problems. it will be easier to complete them.  
Acid Base 8 – Titrations.pdf
View Download
 
Acid Base 8 – Titrations Key p.pdf
View Download

3
.  Please complete the 
Determining pKa and Indicators.pdf worksheet below with the lecture below and or key below. 
 
Determining pKa and Indicators.pdf
View Download
 
Determine Ka and Indicator key p.pdf
View Download
 
Determining pKa and Indicators.pdf should look familiar!
     The point of the worksheet is to derive and use the Henderson Hasselbach equation for point #2 in titration   
     problems and to review that acid/base indicators (chromophores with pi stacking!!!!!!) are also acid base buffer       solutions.  Deciding which indicator to use is based on their individual Ka that best intersects the asymptotic     
     region that is closest to equivalence point.
 
 We determine Equivalence points (stiochiometric endpoints: H+ = OH )  by pH probes AND we estimate Equivalence points by determining the “end point” of  titration by using acid base indicators (that are weak acid conjugate pairs themselves.
                                     REMEMBER THAT INDICATORS provide us as approximation 
                                                 of the equivalence point called an endpoint!
 
We write indicators in acid base chemistry with the following designation:
 
                                                                          HIn    <—–>    H+    +        In
                                                                               Conjugate Acid                                    Conjugate Base
* In the above equation, the colors are represented correctly of the acid/base indicator Litmus.
What makes them so important is these weak acid/base equilibrium solutions (indicators) have different colors in their conjugate acid and conjugate base form. The molecular structure of these macromolecules allosterically change their amount of conjugation (amount of double – single bonds) in the presence of H+ or OH.
 
When an appropriate acid / base indicator is used in a titration its color change occurs when there is about 50% of  HIn and 50% In is present.  This is the Half- equivalence point, which is when the ph = pka of the indicator!!!
Determining pKa and Indicators lecture:
Ammonium Chloride Titration lecture:
 
Play in youtube and under the description you can click on the timecode to take you to the 
point in the lecture you want to review.
 

End of week nine and End of Quarter 3!