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Q2: Week 2  – 11/22 – 11/23

                                                                                                                                                                                                Jump toTuesday,   Wednesday,  Thursday, Friday                                                                                                                              ______________________________________________________________

11/22 – Monday – B Day – 2, 3b/4 Lab 

Main focus –                                                                                                                                                         

     a) To review the weak acid /strong base Titration

     b) To identify buffer solutions

     c) To use the Henderson – Hasselbach to answer point 3 questions

Period 2:  Collect Titration quiz (from the form).

1. Review Lab 11 and the homework form (another weak acid/base titration).

2. Review Past 2 Acid Base Homeworks – YOU MUST BE ABLE TO IDENTIFY which Points on the titration graph ( 1 – 5) you are working with.  

Acid Bases Pre-Titration key p.pdf
View Download

Titration Graph Lab questions Key p .pdf
View Download

Period 3/4: Collect Titration quiz (from the form).

1. Same as above


Today’s Notes:

From this weekends homework:

Reaction during the titration – Driven by the strong Acid to completion to the equivalence point
                        H3O+      +     C6H7O2–           – –>       HC6H7O         +      H2
                      strong acid      Weak Conjugate Base      —>    stronger conjugate acid                                                                                         
                          Reaction that occurs at the equivalence point – Equilibrium reached (NOT DRIVEN)
                                    HC6H7O2     +    H2O    <—>     C6H7O2-1       +       H3O+
                             conjugate acid ionizes water                                                     Lowers pH at equivalence
Strong Acid Strong Base
 ~Lab 10
          pH = 7 @           equivalence                 only spectators that DO NOT ionize water
 Weak Acid  Strong Base
~Lab 11,
   pH  >7 @ equivalence                Conjugate Base produced reacts with water                                                              to produce OH-
 Strong Acid  Weak Base
~Last nights HW
   pH  <7 @ equivalence                Conjugate Acid produced reacts with water
                                                      to produce H3O+

The  Blood buffers the blood pH so that you survive!!!  There are so many organic molecules that have acidic or basic properties that would cause death in our aqueous plasma (fluid part) of our blood.

The main buffer in our blood that prevents large pH changes if the following conjugate acid base pair:

   Conjugate Acid                      Conjugate Base
            H2CO3            <—>          H+  +  HCO3-1
   Neutralizes Bases                  Neutralizes Acids  



        The pKa of  H2CO3 = 6.1   The Ka of this week acid = 10 3.8   = 1.58 x 10-4
Blood is buffered at pH of about 7.4.  What is the ratio of conjugate base to conjugate acid in this buffered solution?
                                                                   pH = pKa + log [A]/[HA]
                                                                   7.4 =  6.1  + log [HCO3-1]/[H2CO3]
                                                                     1.3 = log [HCO3-1]/[H2CO3]
                                                                   10X to both sides of the equation
                                                                          101.3 = [HCO3-1]/[H2CO3]
                                                                                    =    19.9     :      1        ratio
                               *Normal human blood has about a 20 : 1 ratio!
                                     What would this look like on a titration curve?


Sodium Carbonate / HCl (weak base / strong acid Titration): The blood buffer!

End Of Thursday!


                                                                Side by side comparison of the 2 types of titrations:







11/23 – Monday Homework: – 


1. Please complete with me the Determining pKa and Indicators.pdf worksheet. Please review with key and or the posted video that reviews some parts of the worksheet worksheet.                                                                                                                           
Determining pKa and Indicators.pdf
View Download
Determine Ka and Indicator key p.pdf
                                                                                                                                                                                                                                New Skills
pKa = pH at half equivalence point 
                    a) determining Ka of Acid Graphically
                    b) determining indicator based on pKa
                    c) Henderson – Hasselblach equation derivation                                                                                                                                                                                                                                                                                                                                                              2. Please predict the following the 5 points on piece of graph paper given the following titration.  Show all work for each point. This will be collected tomorrow. There is no form for this assignment.    
Point 1 = initial pH = 11.4 (given)
Point 2 = half equivalence
Point 3 = buffer position (when 8.0 ml  of titrant has been added )
Point 4 = equivalence point
Point 5 = final pH.                                                                                                                                                                        
Your graph will predict the titration curve for the following titration:                                                                                                                                                                                                                                                                                                                                                                             25.0 ml of a 0.30 M NH3 solution is titrated with a
                                                  total of 38 ml of a 0.25 M solution of HCl
You will need the following additional data to complete the prediction:                                                                                                                                                                                                                                                                                                                                                 The Ka of NH4+ = 5.6 x 10-10 
      The initial pH of the analyte solution is pH = 11.4
      The pH at the equivalence point = 4.2   
      Please predict point 3 when 8.0 ml  of titrant has been added                                                                                                                                                                                                                                                                                            If you need more graph paper:
      graph paper.pdf                                                                                                                                                                                                View Download                                   

Determining Ka, Indicator worksheet review:

End of Monday.


11/23 – Tuesday – A Day – 2/3a Lab, 4

Main focus –                                                                                                                                                         

    a) To review a weak base strong acid prediction titration curve of 5 points.

    b) To perform a weak base strong acid titration (Lab 12)

Period 2/3: 

1. Review the Weak base strong acid titration prediction graph
2. Perform Lab 12 – (Weak base Strong Acid Titration)                                                                                                                                                                                                                                                                                                                                                          Period 4: 
1. Same as above.

If Last nights homework was a disaster please do not hand it in.  I will have everyone do another prediction graph next week . Please review the key when you get a chance. The titration we did today we will do in class next Monday!

Weak Base Strong Acid Prediction 21-22 key p.pdf                                                                                                        View Download   


Lab 1 2 – Weak Base / Strong Acid Titration

In this Lab we were trying to determine the concentration of a the weak base solution using a KNOWN concentration of a STRONG Acid.  I tried to make a 0.30 M solution of the weak base but because my stock solution was diluted from time our actual titration will be a little different.
Thus 25.0 ml of a unknown M NH3 solution is titrated with a total of 38 ml of a 0.25 M solution of HCl
On the Printed graph please number your work! 
1: Determine the equivalence point of the titration. (Identify of the graph)
2: Determine the concentration of the acid.
3: Determine the end point of the titration if phenolphthalein was used. (Identify on the graph)
4: Determine the halfway equivalence point. (Identify on the graph)
5: Confirm the final pH of the titration.
6: Confirm the initial pH of the titration. YOU CANNOT DO THIS STEP!!!!!!!(In the spring)
7: On the first 4 points of the titration curve (1 = initial pH, 2 = halfway equiv., 3 = buffer position, 4 = equivalence               point,) determine the percentage of the Conjugate Acid/ Conjugate Base / OH
8: Write the net-ion reaction.
9: Determine the Ka of the Acid.

10. Confirm the pH of point 3 when _____ml of acid was added to the weak base.


11/24 – Tuesday Homework: – 

1.  Please enjoy your family and dispell any tryptophan myths!

Tryptophan is an essential amino acid:
It is found in all foods that have complete set of amino acids (that out body cannot make) !


Based on the above chart you can see that turkey does not have the greatest amount of proteins with tryptophan.
AND NO tryptophan does not make you sleepy!!!  If it did vegetarians would always be asleep because they love tofu which is made of soybeans!
Also if that myth was true turkey sandwiches would have warning labels like, 
                                                        “Do not operate heavy machinery while digesting turkey!”
                                         How many tryptophan related accidents would we have on Thanksgiving?
Acidic or Basic Foods:


11/24 – Wednesday – A Day – THanksgiving Eve – Gobble




11/18 – Thursday – B Day –  Happy Thanksgiving!!!




11/19 – Friday – A Day – Post Thanksgiving.