Wow! Look!  Types of Chemical Reactions from a different perspective i.e. a different book.

I.    Precipitation Reactions:

    1. Solubility Rules: (OH 1-A) See pg. 396 Table 12.1.

Be able to use to predict precipitation reactions

    1. Mix Solutions of Ba(NO3)2   +    Na2CO3

      2. What happens?

      Ions present?

      Possible PPT’s?

      Real PPT?

      Net Ionic Equation:

              Ba2+ (aq)   +    CO32-(aq)   à  BaCO3(s)

    2. Mix BaCl2, NaOH.

What happens?

Ions present?

Possible PPT?

Real PPT?

II.    Acids and Bases
    1. What is an acid?

      2. Forms H+ ions in H2O

      What are two types? What is the difference?

      Strong – 100% ionization ß text is wrong

      Weak – Partial ionization

      What are the classic strong acids?

      (OH – 2A)

      What are the classic weak acids?

      See page 400 Table 12.2

      (hint: Know the strong ones, and the others are weak)

      1 M HCl is all H+ and Cl-

      1 M HF is [HF] = 0.97 M, [H+] = [F-] = 0.03

    2. What is a base?

      3. Something that forms OH- in H2O

      There are strong and weak bases. ß know the strong ones

      What is a classic weak base?

      What is an amine?

      [CH Junk] R-NH2 + H2O ßà RNH3+ + OH-



    3. Acid-Base Reactions
    1. Strong Acid and Strong Base

      2. The classic is…

      HCl + NaOH

      NET Ionic {}

    2. Strong Base – Weak Acid

      3. OH-(aq) + HF(aq) à H2O + F-(aq)

    3. Strong Acid – Weak Base

      4. H+(aq) + NH3(aq) à NH4+(aq)

    4. Weak Acid – Weak Base

                HC2H3O2 + CH3NH2 ß à CH3NH3+ +C2H3O2-
                    [CH3COOH]

IN EACH CASE; THE SPECIES PRESENT AT HIGHEST CONCENTRATION IS WRITTEN AS REACTANT.

See rules on page 404

Demo: Sulfuric Acid + Barium Hydroxide
2H+(aq) + SO4 –2(aq) + Ba2+(aq) + 2OH-(aq) à BaSO4(s) + 2H20

At end point, there are no ions.

III.    REDOX: LEO says GER

Loss of e- oxidation Gain of e- reduction

    1. Know rules on page 406 ß READ ‘EM!

      2. These are "Pseudocharges"

      What is OX# of following?

      02, Fe3+, Na2S, KH, H2SO4, Cr2O7 2-

    2. Another Definition of Ox & Re

Oxidation: Increase in OX- Number

Reduction: Decrease in OX- Number

Assign Oxidation #’s to all the following:

                               

Cl- is oxidized – we call HCl the reducing agent

N5+ is reduced – we call HNO3 the oxidizing agent.

Read Top page 408

KNOW HOW TO BALANCE REDOX REACTIONS – FOLLOW ME! [ACID type FIRST]

Given: Sodium Dichromate reacts with KI to form Cr3+ and Iodine.

    1. Write the NET ionic form of all species –

      2. Don’t balance! (Do without H+ first!)

      Cr2O72-(aq) + I-(aq) à Cr3+(aq) + I2(s)

    2. Split into 2 half equations

      3. I-(aq) à I2(s)  OX:
      Cr2072-(aq) à Cr3+(aq)  RED:

    3. Balance everything but O, H

      4. 2I- à I2
      Cr2072- à 2 Cr3+

    4. Do an Oxygen Balance,

      5. Add H2O to the side lacking "O"

      2I- à I2
      Cr2O72- à 2Cr3+ + 7H2O

    5. Do a Hydrogen balance,

      6. Add H+ to the side lacking H
      2I- à I2
      14H+ + Cr2O72- à 2Cr3+ + 7 H2O

    6. Do a charge balance – Add e- to the side lacking e-

      7. 2I- à I2 + 2e-
      14H+ + Cr2072- + 6 e- à 2Cr3+ + 7H2O

      Note: 2Cr3+ = Green Ion, What color is Cr2072-?

    7. Multiply each ENTIRE ½ reaction by an appropriate #, so the e- cancel out…

      8. Then ADD ‘EM!

    8. IF you want the solution basic add OH- to both sides to "zap out" H+’s

    9. Check charge and atoms same on each side

Know Disproportionation page 413

Page 425 #35 a (Basic)

1.    ClO- + CrO2- à Cl- + CrO42-
2.    ClO- à Cl-
        CrO2- à CrO42-
3.    Same as 2.
4.    ClO- à Cl- + H2O
       CrO2- + 2H2O à CrO42-
5.    2H+ + ClO- à Cl- + H2O
       CrO2- + 2H2O à CrO42- + 4 H+
6.    2H+ + ClO- + 2e- à Cl- + H2O
       CrO2- + 2H2O à CrO42- + 4H+ + 3e-
7.    6H+ + 3ClO- + 6e- à 3Cl- + 3H2
       2CrO2- + 4H2O à 2CrO42- + 8H+ + 6e-
                                                                   
    ADD THE ABOVE 2 AND CANCEL OUT COMMON H+, H2O, e- TO GET
         

         8.   
       

SOME FUN!

IV. Solution Stoichiometry

(See Page 414 and Figure 12.6)

    1. What volume is needed of a 0.200 M CuSO4 solution to react with 50.0 mL of 0.100 M NaOH [OR (Ba(OH) 2)]?

      2. Write the reaction:

      0.200M         0.100M            &     50.0mL

      Find mL

      3. [OR (Ba(OH) 2)]? How would this change it?

Suppose 22.0 mL of 0.150 M K2Cr2O7 is required to react with a sample weighing 5.00 g.

Find % I- in sample

Moles of  

Mass of

= 2.51 grams I-

So

NEED TO KNOW IDEAS ON PAGE 418 AND DEFINITIONS!

WATCH OUT FOR DIPROTIC ACIDS OR DIBASIC BASES!

DIPROTIC ACIDS:

DIBASIC Bases:

SO YOU WANT TO TRY A SELF TEST FROM ANOTHER BOOK? Go to the problem solving center to take the test. CLICK HERE!

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Lee Marek