Oxidation Reduction Reactions

Chem II: Block 10.14.14

Infinite Campus:

• Chemical Reactions Exam

• Replacement Labs (30pts.)

Objectives:

• I can predict and simplify double replacement reactions.

• I can distinguish between oxidation and reduction reactions.

• I can balance oxidation-reduction (Redox) reactions.

Double Replacement Reactions

• Complete 4.24 problems.

Solubility Ranges

• Soluble: > 0.1M concentration of solute dissolved in solution.

• Insoluble: < 0.0001M concentration of solute dissolved in solution.

• Slightly soluble: between 0.0001M and 0.1 M of solute dissolved in solution.

Double Replacement Reactions

• Why is it some ionic compounds are soluble in water and others are not? Use the image below to come up with an educated guess.

Aqueous Reactions

Reactions that occur in aqueous solutions:

1. Double Replacement Reactions

2. Oxidation-Reduction (Redox) Reactions

3. Acid-Base Reactions

Oxidation Reduction Reactions

Oxidation Reduction Reactions

• Also called Redox Reactions

• One reactant becomes oxidized (lose electrons) and one reactant becomes reduced (gains electrons).

(spontaneous /non-spontaneous).

• Transfer of electrons from the oxidized reactant to the reduced reactant.

LEO goes GER animals.nationalgeographic.com

LEO: lose electron(s) oxidized

GER: gain electron(s) reduced

Redox Reactions

Ex. 2Ca + O

2

-----> 2CaO

How do you know which reactant is oxidized (LEO) and which reactant is reduced (REO) in a redox reaction?

Assigning oxidation numbers for elements in the reaction.

Oxidation Number Rules

1. For an atom that is not combined with any other kind of atom its oxidation number is zero.

Ex. Mg 0 , Fe 0 , H

2

0 (all diatomic molecules)

2. A monatomic ion’s oxidation number is equal to its charge.

Ex. Mg 2 = oxidation number is 2+

Cl 1= oxidation number is 1-


3. The sum of the oxidation number for all atoms in a compound (ionic or covalent) is zero.

Ex. H

2

1 O -2 = zero Ex. NaCl 1= zero


4. The oxidation number for oxygen in a compound is -2.

Ex. C 4 O

2

2-

*Exceptions: a. peroxides (O

2

) 2the oxidation number is -1

Ex. H

2

1 O

2

1a. Bonded to F: oxidation number is positive

(1 + or 2 + )

Ex. O 1+ F 1F > O electronegativity

Electronegativity Values


5. Hydrogen:

• When bonded to a non-metal it is 1+

(most common)

Ex. H 1 Cl 1-

• When bonded to a metal it will be 1.

Ex. Mg 2+ H

2

1


6. Polyatomic Ions:

The sum of the oxidation numbers of all atoms in a polyatomic ion has to equal the charge on that ion.

Ex. (Cl 5 O

3

2) 1-


7. In covalent compounds that do not contain hydrogen or oxygen, the most electronegative element has an oxidation number equal to its charge as an ion.

Ex. P 5 Cl

5

1-

,

Cl> P with electronegativity

Electronegativity Values


Infinite Campus:

• Chemical Reactions Exam

• Replacement Labs

Due:

• Element’s Oxdiation #s: qts. 4.49; 4.50 from text

Objectives:

• I can distinguish between oxidation and reduction reactions using oxidations numbers.


a. SO

2

Oxidation Numbers: qts. 4.49

b. COCl

2 c. (MnO

4

) : Mn =7+ O = 2d. H(BrO): O = 2-; Br= -1; H = +1

*(BrO) 1=hypobromite ion e. As

4 f. K

2

O

2

: O = 1- (peroxide ion); K= 1+

a.

b.

c.

d.

e.

f.

Oxidation Numbers: 4.50

Oxidation Numbers: Assessment

Assign an oxidation number for each element in the examples below:

1. H

2

2. Cu

3. Fe

2

O

3

4. N

2

O

5

5. H(NO

3

)

6. CCl

4

8. Cr(CO

3

)

9. OF

2

10. Ca(OH)

2

Oxidation Numbers: Assessment

Assign an oxidation number for each element in the examples below:

1. H

2

2. Cu

3. Fe

2

O

3

4. N

2

O

5

5. H(NO

3

)

6. CCl

4

8. Cr(CO

3

)

9. OF

2

10. Ca(OH)

2


Due:

• Oxidation/Reduction Worksheet

Objectives:

• I can distinguish between oxidation and reduction reactions using oxidations numbers.


Redox Reactions

Ex. 2Ca + O

2

-----> 2CaO a. Assign oxidation numbers for each element on on reactant and products side. b. Identify and explain which element was reduced in this reaction.

c. Identify and explain which element was oxidized in this reaction.

Redox Reactions: Half Reactions

Ex. 2Ca + O

2

-----> 2CaO

Half-Reactions: Separates/identifies the oxidized and reduced reactions that occur simultaneously in nature-why called Redox reactions.

Oxidized Reaction:

Reduced Reaction:

Redox Reactions Practice Problems

1. Classify each half reaction as oxidation or reduction. a. Ba ----> Ba 2+ + 2eb. 2H 1+ + 2e- -----> H

2

2. Using oxidation numbers, predict if the reactions below are redox reactions.

a. Fe (s) + Cu(SO

4

) (aq) ----> Fe(SO

4

) (aq) + Cu (s) b. NaCl (aq) + Ag(NO

3

) (aq) ---> Na(NO

3

) (aq) + AgCl (s)

Redox Reactions: Half-Reactions

Balancing Redox Reactions

• Must conserve mass and charge.

• Establish half reactions to ensure electron transfer is balanced.

• Only include substances undergoing redox in the half-reactions.

• Redox reactions usually occur in acidic or basic solutions. (Balance differently).

Balancing Redox Reactions: Acidic Solutions

Cu (s) + NO 3(aq) ----> Cu 2+ (aq) + NO

2

(g)

Chem II: 9/24

Objectives:

• I can predict redox reactions by assessing oxdiation numbers of elements in the reaction.

• I can balance redox reactions using half reactions.

Homework:

• Balance Redox Reactions (Acidic/Basic)

• Redox Quiz tomorrow

Redox Reactions

• Ag(NO

3

) + Cu --> a. Predict Products b. Assign Oxidation Numbers to validate if redox reaction.

c. If redox, identify and explain what is oxidized and what is reduced.

Balancing Redox Reactions: Acidic

Cu (s) + NO 3(aq) ----> Cu 2+ (aq) + NO

2

(g)


(Cr

2

O

7

) -2 (aq) + I (aq)----> Cr 3+ (aq) + (IO

3

) (aq)

Balancing Redox Reactions

• Balance half reactions with peers via gallery walk.

• Self-assess peers work by making changes where needed.

• Record your answers on a separate sheet of paper.

Chem II: 9/25

Objectives:

• I can predict redox reactions by assessing oxdiation numbers of elements in a reaction. (Quiz today)

• I can balance redox reactions using half reactions in acidic or basic solutions.

• Review Chemical Reaction Exam

Homework:


Balancing Half Reactions


(Cr

2

O

7

) -2 (aq) + I (aq)----> Cr 3+ (aq) + (IO

3

) (aq)

Chem II: 9/26

Objectives:



Homework:


Redox Reactions: Gallery Walk

Chem II: 9/27

Objectives:



Homework:


Balance Redox Reaction (acidic)

Balance using half reactions the following reaction in acidic solution.

20.21: example d

Redox Reaction (basic solution)

Balancing Redox Reactions: Basic

NO

2

(aq) + Al(s) -----> NH

3

(aq) + Al(OH)

4

(aq)

Chem II: 9/30

Infinite Campus Update:

• Redox Classification Quiz -17pts

• Balance Redox Rxtn (acidic)-5pts

Objectives:


• Review Redox Reaction Quiz and Bell Ringer


• Set-up Redox Lab (Use Buret for titration)

Homework:

• Balance Redox Reactions

Midterm Exam Concepts

• Molarity vs. Molalilty

• Classification of Mixtures (colloids, suspensions, solutions)

• Assigning Oxidation Numbers to substances

• Identifying and Balancing Redox Reactions

• Stoichiometric Calculations with Redox Reactions

Balancing Redox Reaction (basic)

Gallery Walk:

Balancing Redox Reaction in basic solution.

Bell Ringer: Redox Reaction. (acidic)

Redox Classification Quiz

Chem II: 10/1

Objectives:



• Set-up Redox Reaction Lab

Homework:

• Read procedures and complete pre-lab questions

Chemical Reaction Exam

Balancing Redox Reactions (Basic)

NO

2

(aq) + Al(s) ----> NH

4

+ (aq) + AlO

2

(aq)

Balancing Complete Redox Reactions

H

2

S + H(NO

3

) -----> S + NO + H

2

O (acidic)

Redox Titration Lab

H

2

O

2

+ KMnO

4

Pre-Lab:

+ H

2

(SO

4

)  Mn(SO

4

) + K

2

(SO

4

) + O

1. Practice reading and working stopper on Buret.

2

(Measure out 15 mL of water 3xs from buret, validate volume with graduated cylinder.

+ H

2

O

2. Complete pre-lab questions from lab

Chem II: 10/2

Objectives:

• Complete and assess Redox Lab

Homework:

Complete Post Lab Questions

Chem II: 10/4

Objectives:

• Chemistry II Midterm

• Analyze Redox Reaction Lab

Homework:

Have a nice fall break. 

Chem II: 10/14

Infinite Campus Update:

• Balance Redox Reaction (Basic) Quiz

• Redox Lab: Hydrogen Peroxide Analysis (24pts.)

• Chemistry Midterm Exam (35pts.)

Objectives:

• Review Quiz and Midterm

• Address Redox Lab

• Electrochemistry : Redox Application

Balancing Redox Reactions (Basic)

NO

2

(aq) + Al(s) ----> NH

4

+ (aq) + AlO

2

(aq)

Stoichiometry

2 H

2

O + NO

2

+ 2Al(s) ----> NH

4

+ + 2AlO

2

www.larapedia.com

Balanced Redox Reactions (Basic)

2 H

2

O + NO

2

+ 2Al(s) ----> NH

4

+ + 2AlO

2

a. If we start with 3.8 moles of NO

2 many moles of AlO

2

-

how could be produced?

b. If we want 13 grams of NH

4

+ ion, how many grams of Al would we need to start with?

Chemistry Midterm Exam


#18.

Mn 2+ (aq) + Na(BiO

3

) (s) ---> Bi 3+ (aq) + MnO

4

-


#19.

Cr(OH)

3

(s) + ClO (aq) ---> ( CrO

4

) 2(aq) + Cl

2

(g)

Redox Titration Lab http://www.webassign.net

Redox Titration Lab

H

2

O

2

+ KMnO

4

+ H

2

(SO

4

)  Mn(SO

4

) + K

2

(SO

4

) + O

2

+ H

2

O

5 H

2

O

2

+ 2 KMnO

4

+ 3 H

2

(SO

4

)  2 Mn(SO

4

) +K

2

(SO

4

) + 5 O

2

+ 8 H

2

O

4

5

2

3

1

Redox Titration Lab Results

Lab Group Avg. volume of KMnO

4

Avg:

% of H

2

O

2 solution in

% Error

% Error

:

Redox Titration Lab Results

Conclusion:

1. a. How accurate was your experimental value with the actual value of % hydrogen perxoide in solution. b. Explain reasons for degree error.

2. How accurate was the class’ data from one another?

3. If you could repeat the lab what modifications would you make and why.

Oxidation Reduction Reactions

Stoichiometry

Related documents

Products

Support

Oxidation Reduction Reactions

Stoichiometry

Related documents

Add this document to collection(s)

Add this document to saved

Suggest us how to improve StudyLib