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Week 11  – 11/8 – 11/12

                                                                                                                                                                                        Jump toTuesday,   Wednesday,  Thursday,   Friday                                                                                                                              ______________________________________________________________

11/8 – Monday – A Day – 2/3a Lab, 4 

Main focus –                                                                                                                                                         
                                                  

     a) To define Lewis acid/base definition and weak acid /base equilibria

     b) To introduce the auto – ionization of water, pH, pOH, Kw, -log, 10-x

Period 2/3: 

1. Complete the Lewis acid/base definition in explaining the CO2. 

2.  Review weak acid/base equilibria

Conjugate Acid Base Pairs and Complex ions new key p.pdf
View Download

3.  Started the Auto ionization of water lesson – pH, pOH
 
        a) Demo – pH probe demo with straw and washing soda
                            Pictures of the pool chemicals
                             copper ions pH probe
 

Classwork:
Acid and Bases Intro packet new.pdf
View Download
                                                                                                            

Period 4: 

1. Complete the Lewis acid/base definition in explaining the CO2. 

2.  Review weak acid/base equilibria / homework

3.  Started the Auto ionization of water lesson – pH, pOH
 
        a) Demo – pH probe demo with straw and washing soda
                            Pictures of the pool chemicals
                             copper ions pH probe
        b) Started Pages 3 and 4 of the intro packet.

Notes for today:

This is the mechanism of how CO2 acts an acid by the the Lewis Definition.

The most complete definition is the Lewis acid base definition because there are acids and bases that DO NOT HAVE protons to donate or possibly accept BUT create acidic conditions or Basic Conditions.
 
In table K they list CO2 an acid but it had no protons to donate?  It is an acid because when we bubble CO2 in water the conditions in water become more acidic.  
 
                    CO2  +   H2O             ——>              intermediate                  ——>             H2CO3
                                                                                                                                                                                      then…..
                                                    H2CO  +   H2O  <——>  H3O+  +   HCO-1
 
CO2 can accept a pair if electrons (JUST LIKE a proton!!!) so the best and most complete definition of acids and bases is the LEWIS acid base definitions! Lewis acids like CO2 are electron acceptors while bases like water in the example are electron donators!!
 

CO2 acts an acid by the the Lewis Definition.

The most complete definition is the Lewis acid base definition because there are acids and bases that DO NOT HAVE protons to donate or possibly accept BUT create acidic conditions or Basic Conditions.
 
In table K they list CO2 an acid but it had no protons to donate?  It is an acid because when we bubble CO2 in water the conditions in water become more acidic.  
Back to the pumpkin Stoichiometry from last week:

C2H2 (g)  +   5/2O(g)    —> 2CO2 (g)   +  H2O (g)

                                                                
                                             0r
 
2C2H(g)  +    5 O(g)    —> 4CO2 (g)   +  2H2O (g)
The chemical reaction that exploded the pumpkin was combustion or redox but the reaction the made fuel, C2Hwas?
What kind reaction is this?
 

                       CaC2 (s)   +   2H2O (l)           —–>                C2H2 (g)    +    Ca(OH)2

The Arrhenius definition although a good start to defining acids and bases is not complete because we have chemicals that do not have any hydroxide ions in their structure (like NaOH) but will create acidic or basic conditions in water.  In the case above,  the hydroxide ion (OH) was produced by the action of the  carbide ion (C2-2).   So the Bronsted-Lowry definition is a more complete definition because it includes those chemical species that Produce the Basic or Acidic conditions by Accepting a proton or donating a proton.                                                                                                                                                                                     
In the case above the carbide ion (C2-2) ion is the Bronsted-Lowry base (the carbide ion accepted the proton.) and the water is the Bronsted- Lowry acid (because water DONATED A PROTON) (
 
*Notice that acids must have electron deficient hydrogen to donate protons (H+).
 *Notice that Bases must have an ability to accept protons (H+).  Having a lone pair of electrons or having a negative           charge helps attract the protons!
 

                  The result of this acid base reaction is that acetylene C2H2 was produced.                                                                                                                                                                                                                                      Notes for auto – ionization of water:  

*Connections   Stoichiometry (mole ratio) continues with Acid/Base Reactions.  The connection we need to make is that salts that are soluble and that produce a hydroxide ion (OH) into an aqueous solution are bases.  These are important ions because they can upset the balance of H+ and  OH in water.  Remember that these are naturally occurring ions that occur in water.  
This called auto-ionization of water.
 
                                                      H2(l)  →    H+ (aq)   +   OH– (aq)             Kw =  1 x 10-14
                                                             Proton               Hydroxide
 
                                                                                         or
 
                        H2(l)  +  H2(l)  →    H3O+ (aq)   +   OH (aq)        Kw =  1 x 10-14
                                                             Hydronium         Hydroxide
                                 
                  From 2 reactions above which are really the same you can see ONE H+ or H3O+ for every ONE OH.
 
                    Acids will increase the Hor the  H3O+ concentration above normal* conditions.
 
                               Bases will increase the OH– concentration above normal* conditions.
 
*Normal conditions refer to water that is NEUTRAL : (  Hor the  H3O=   OH– )  = pH = 7
 
                                                                 H2(l)  →    H(aq)        +   OH– (aq)                                                                   
                                H2(l)  +  H2(l)  →    H3O(aq)   +   OH (aq)   
 
                                        Keq =   [Products]   =  Kw = [H+ H3O+][OH]
                                                     [Reactants]
 
*We can use H3Oand H+ interchangeably.  I will write Hgoing forward but remember I can use H3Oat any time and it would mean the same thing.  (Whether you have a free proton or a a proton held by water does not matter)
Now the value of Kw (equilibrium constant for the auto-ionization of water) equals =  Kw = 1 x 10-14
                                                                                      
                                                                      Kw = [ H+ ]    x     [ OH]                                                                                                                                 
                                           1 x 10-14   = [ H+]     x    [ OH]
 
If one Hdissociates for every ONE OH–  H2(l)  →    H(aq)        +   OH– (aq)    then:                                
                                           1 x 10-14   =  [ H+]     x    [ OH]                                                                                                                                                                             
                                          1 x 10-14    =  [1 x 10-7]     x    [1 x 10-7 ]                                           
                
As you can see the concentration (molarity, M) of Hand  OH–  ARE THE SAME IN PURE WATER! 
                                                       
They must be the same concentration to equal 1 x 10-14 !
Remember when you multiply exponents you add!
 
*THIS is WATER AT NORMAL CONDITIONS.                           
 
 Now we use a convention to measure this balance or unbalance of ions in water.  It is called pH.
 
                                     pH = – log (base 10) of the Hor  H3Oconcentration.
 
                            Pure water at 4 degrees Celsius the [H+] or  [H3O+]  = 1 x 10-7
                            if you put  -log (1 x 10-7) in your calculator you will get :  pH  = 7
 
So basically pH is a numerical system that measures “stuffs” the entire concentration (small value) into a exponent (base 10) AND MAKES IT positive for Ease  
 
                                                                            pH = – log  [H+ 
 
a)What if the [H+] = 1 x 10-5  ?  What is the pH?   Is this an acid, basic or neutral solution?
 
b)What if the [H+] = 0.001  ?  What is the pH?  Is this an acid, basic or neutral solution?
 
c)What if we have a [HCl] = 0.1 M   What is the pH?  Is this an acid, basic or neutral solution?
 
d)What if we have a [HCl] = 5.6 x 10-6   What is the pH?  Is this an acid, basic or neutral solution?
 
e)What if you have [NaOH] = 0.001    What is the pH?  Is this an acid, basic or neutral solution?                                                                 
e)What if you have [NaOH] = 3.34 x 10-5   What is the pH?  Is this an acid, basic or neutral solution?
 
*Notice the above problems are strong Acids and Base, which means complete dissociation.
 
 answers on bottom of today’s homework post..   

                                                                                                                    

Auto-ionization of water lessontoday’s Lecture and also part of tonights homework.

 

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11/8 – Monday Homework: – 

1.  Please view the video above from 24:45 till the end and then complete the page 4 of the acid / base intro packet and review the key.                                                                                                                                                                                                            
Acid and Bases Intro packet new.pdf
 
Acid Bases Packet Intro Key 1718 p.pdf
View Download
 
2.  Please answer the questions below (answers are posted below):                                                                                                                                                                          
a)What if the [H+] = 1 x 10-5  ?  What is the pH?   Is this an acid, basic or neutral solution?
 
b)What if the [H+] = 0.001  ?  What is the pH?  Is this an acid, basic or neutral solution?
 
c)What if we have a [HCl] = 0.1 M   What is the pH?  Is this an acid, basic or neutral solution?
 
d)What if we have a [HCl] = 5.6 x 10-6   What is the pH?  Is this an acid, basic or neutral solution?
 
e)What if you have [NaOH] = 0.001    What is the pH?  Is this an acid, basic or neutral solution?                                                                 
e)What if you have [NaOH] = 3.34 x 10-5   What is the pH?  Is this an acid, basic or neutral solution?
 
*Notice the above problems are strong Acids and Base, which means complete dissociation.

 

Answers for question in notes above.

a) pH = 5   Acidic solution (below 7)
b) pH = 3   Acidic solution (below 7)
c) pH = 1    Acidic solution (below 7)
d) pH = 5.25  Acidic solution (below 7)
e) pOH = 3  thus  pH = 14 – 3 =  pH = 11  Basic solution (above 7 – more OH than H+)
f) pOH = 4.48  thus pH = 14 – 4.48 = 9.52  Basic solution (above 7 – more OH than H+)

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11/9 – Tuesday – B Day – 2, 3b/4 Lab 

Main focus –                                                                                                                                                         
                                                  

    a) To calculate the hydronium or hydroxide concentration from pH.

    b) To calculate the pH of a strong acid or strong base from its molarity.

    b) To identify an acid/base indicator as a conjugate acid /base pair.

Period 2: 

1.  Review of Table L, conjugate base strength in terms of strength of acid
 
        a) Complex ions acidity/ backside of conjugate acid worksheet.
        b) Basic (washing soda) , Acidic, neutral salts
 
2.  Review page  from the acid/base intro packet.
                                                                                                                               
3. Acid / Base indicators –  Complete the last page (4) of the packet
 
           a) straw and bromothymol blue demo
           b) phenolphthalein – rough titration.

 

Acid Bases Packet Intro Key 1718 p.pdf                                                                                                                                                       View Download                                                                                                      

Period 3/4: 

Same 1, 2, 3 above.
Take a RAT # 1 
RAT #1 Acid Base Intro Basics 
           You will take the quiz twice.  
 
        – First time –  Complete the Form Below individually –
 
        – Second time –  Complete with  a group using a scratch ticket

 

                                                                                                                                                
 Here are some expensive pool chemicals that change the pH.
                                  Na2CO3                                                                              NaHSO4
                                                                                                                      

Acid Base Indicators Presentation:

Today’s lessontoday’s Lecture 

 

____________________

11/9 – Tuesday Homework: – 

1.  Please complete the  SIDE 1 – 

Stiochiometry 5a – Acid Base Reactions new.pdf worksheet with using the posted video below.  
 
This is a lesson in writing Net Ion Acid/Base Reactions!
 
*Remember that soluble salts (aq) were never written together in NET ION EQUATIONS while the precipitate (s) are because they do exist in a crystal together.  In Acid/Base the “soluble ” compound is the “Strong” Acid or Base because they completely dissociate just like soluble salts, however weak acids and bases are NOT completely dissociated thus must be written together. WATER IS A NEVER Written dissociated because they barely dissociate!!!
 
Stoichiometry 5a – Acid Base Reactions new.pdf
View Download 
 
Stoichiometry 5a – Acid Base Reactions new Key.pdf
View Download 
 
2. Please complete side 2 of the Stiochiometry 5a – Acid Base Reactions new.pdf with me in the 2nd video below:

Side 2 is about stoichiometry problems using acid base chemistry.

1: Tutorial on Stoichiometry 5a – Acid Base Reactions new.pdf worksheets:
New Side One Lecture : Acid/Base Net Ion Reaction Review:                                                                                                                                         
Okay i made an error on the last net ion reaction. The product of NH3 and H3O+ is NH4+ and water (H2O)! Sorry about that! I was trying to illustrate the reaction between a Strong Acid (H3O+) and a weak base (NH3) thus water would be made in the neutralization reaction. (Thanks Josh Kaplan 2018)                                                                                                                                             

 

2: Tutorial on Stoichiometry 5a SIDE 2: acid base stoichiometry problems!

End Of Tuesday.. 

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11/10 – Wednesday – A Day – 2/3a Lab, 4

Main focus –                                                                                                                                                         
                                                  

     a) To write a net-ion reaction for an acid base reaction.

     b) To Identify ions in salts that are acidic, basic, or neutral.

     c) To perform stoichiometry calculations in acid/ base reactions.

Period 2/3: 

1.  Quick discussion in identifying acid, basic, or neutral salts using the acid/ base definitions.

2.  Take the Acid/Base RAT.

3. Review of Last nights Homework.

Stoichiometry 5a – Acid Base Reactions new Key.pdf
View Download

Period 4: – 

1. Quick discussion in identifying acid, basic, or neutral salts using the acid/ base definitions.

2. Complete the Acid/Base RAT.

 

Notes for acid/ base salts:

Ionic compounds will dissociate into their cations (+) and anions (-) IF THEY ARE SOLUBLE and when they do they can act as either a base or an acid (or not react at all) in water.  If the ions of the salt act as an acid or base they can ionize water as either a hydronium ion (H3O+) or as a hydroxide ion (OH) by following our acid/base definitions. 

For example if we have the following soluble salt:  NH4Cl

                                                                    NH4Cl    —->     NH4+   +     Cl

NH4+WILL IONIZE Water :

                                                      NH4+  +   H2O    —->    H3O+ +   NH3

Since we are increasing the hydronium ion the pH drops and ammonium chloride is an acidic salt.

For example if we have the following soluble salt:  Na2CO3

                                                               Na2CO3     —->   2Na  +   CO3-2

CO3-2 will ionize water:

                                                      CO3-2  +   H2O    —-> HCO3-1   +   OH

Since we are increasing the hydroxide ion the pH increases and sodium carbonate is Basic salt!

What about these expensive pool chemicals????

                                                                                                                                                
 Here are some expensive pool chemicals that change the pH.
                                  Na2CO3                                                                              NaHSO4

3.                                                                                

 

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11/10 – Wednesday Homework: – 

                                                                                                                                                                                                                                1.  Please review the Today’s (or yesterday’s)  RAT .  Expect a new Rat Friday that will include the same information but includes acid/base stoichiometry which your homework was based on!
                                                                                                                                                                                                                                     It will count as a TEST 3 in quarter 1!!! I will take the better of the 2 RATS as Test 3!!!
 I will also drop the lowest test of the quarter so this could be huge!  Friday’s RAT will be the same PLUS I will add i question with a net ion reactions and 2 questions with acid /base stoichiometry.  Please review Tuesday” s homework which reviews both concepts.                                                                                                                                                                                                                         
Here is a blank RAT:      
Acid Base skills RAT 10 questions E009.pdf
                                                                                                                                                                                                                                 Rat #1 – Acid Base Intro Basic Review: You probably do not need too much of this as you reviewed in class  
when you took the group portion of the quiz. I will have a video posted below that reviews every question of the the RAT. You will see similar questions tomorrow.

 

Review of the First Acid / Base RAT

This video has timecode buttons under the description to move to the question you need to review.
You will have to play in Youtube to see the descriptions!                                                                                                                                           

 

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11/11 – Thursday – Veterans Day – OFF – enjoy

 
                                                                                                                   

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11/12 – Friday – B Day – 2, 3b/4 Lab  

Main focus –                                                                                                                                                         
                                                  

     a) To write a net ion reaction in an acid/base reaction

     b) To calculate the volume of base or acid needed to completely neutralize.

Period 2:  – 

1.   We will start and complete the RAT 2 on acid/base basics

2.   Test 2 will be handed back. The key is posted in powerschool. There are points I want make about this test that I will on                  Monday. 

Period 3/4: – 

1.   We will start and complete the RAT 2 on acid/base basics

2.   Test 2 will be handed back. The key is posted in powerschool. We will review this test.                                                                                                           

                                                                                                                    

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11/12 – Friday Homework: –  Make sure you refresh this page to make sure you have the current version!!!!

1. Please review your test 2 with the key posted in Power School.

2.  Please complete the Pre -Titration worksheet and review with the key. Remember that in an Acid/Base titration you need to match every OH- with a H+ and this is called neutralization.  WE also call it reaching the  ” equivalence point” (with pH probes) and the “end point” if we use acid/base indicators.

Acid Base Pre- Titration . pdf
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                                                                                                                                                                                                                            Acid Bases Pre-Titration key p.pdf
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3. Please watch the lecture on Acid/ Base pH Titration Intro lesson:                                                                                                                 
4. Then Read the notes posted below:                                                                                                                                                                                                                                                                                                                                                                                                      5.  View the Strong Acid / Strong Base Virtual Lab below and use the following graph of this titration to complete the           
      following:              
        a) Write the Net Ionic Reaction
        b) Calculate the Molarity of the acid that is being titrated    
                                                                                                                                                                                                                          Strong Base(0.12M) Strong Acid (25.0 ml) Titration.pdf  
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**ACID/BASE TITRATION Curve NOTES:
 
The new skills  are identifying the parts of a Titration curve.  The striking part of the Titration graph is the asymptotic line that occurs as the pH changes becomes exponential changes as the pH nears the equivalence point.  
 
We learned the endpoint in an Acid/Base titration is really an approximation of the equivalence point.  The endpoint refers to the volume of titrant added (Standard Base ) and pH that results when the chemical indicator changes color.  This color change will never be exactly at the equivalence point but it approximates the volume of titrant added if the indicator has a color change on the asymptotic line.
 
Consider the titration in the lecture (Strong Acid/Strong Base).  We used phenolphthalein which has a color change (turns from colorless to pink at pH changes of 8 – 9).  What if we used Thymol blue or Methy red?  
 

Table M

 Do not forget that these indicators are themselves conjugate acid base pairs in equilibrium.

 

In the case of Thymol blue   

Notice in the first Titration which you should recognize as a strong acid / strong base titration, with a pH of the equivalence pH of 7, can utilize both Thymol blue and Methyl red as indicators as the endpoints will be on the asymptotic line.  They would have endpoints with approximately the same volume as the equivalence point. The titration on the right is a Strong Base/weak acid concentration that we will study and do in lab next week. NOTICE THE ENDPOINT IS NOT AT A pH of 7 in this case!

                                                                                                                                                                                           

3. Acid /Base pH Titration Intro lesson:

 

5. Lab 10 Preview – Strong Acid/Base Titration:

 End of Quarter 1!