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.
Chem II Period: 10.30.14
Infinite Campus Update:
• Single Replacement Lab (12pts.)
• Double Replacement Lab (14pts.)
Objectives:
• Chemical Reaction Gallery Walk Completion
• Distinguish between Aqueous Reactions
Chemical Reaction Gallery Walk:
• Assess peers work and document evidence of
participation by recording answers on study
guide.
Chemical Reaction Review
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 ionic compounds differ in the degree of
solubility with water? Use the image below to
come up with an educated guess.
Aqueous Reactions
Aqueous Reactions are reactions that occur in
solution.
Aqueous Reactions:
1. Replacement Reactions
2. Oxidation-Reduction (Redox) Reactions
3. Acid-Base Reactions
*Distinguish between the three types of reactions
above that occur in solution.
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 + O2 -----> 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. Mg0, Fe0, H20 (all diatomic molecules)
2. A monatomic ion’s oxidation number is equal to
its charge.
Ex. Mg2 = oxidation number is 2+
Cl1- = oxidation number is 1-
Oxidation Number Rules
3. The sum of the oxidation number for all
atoms in a compound (ionic or covalent) is
zero.
Ex. H21O-2 = zero
Ex. NaCl1- = zero
Oxidation Number Rules
4. The oxidation number for oxygen in a compound
is -2.
Ex. C4O22-
*Exceptions:
a. peroxides (O2) 2- the oxidation number is -1
Ex. H2 1O21a. Bonded to F: oxidation number is positive
(1+ or 2+)
Ex. O1+F 1- F > O electronegativity
Electronegativity Values
Oxidation Number Rules
5. Hydrogen:
• When bonded to a non-metal it is 1+
(most common)
Ex. H1Cl1• When bonded to a metal it will be 1-.
Ex. Mg2+H21
Oxidation Number Rules
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. (Cl5O32-)1-
Oxidation Number Rules
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.
P5Cl51-, Cl> P with electronegativity
Electronegativity Values
Chem II: Block 10.15.14
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.
• I can balance oxidation-reduction (Redox) reactions.
Oxidation Numbers: qts. 4.49
a. SO2
b. COCl2
c. (MnO4)- : Mn =7+
O = 2d. H(BrO): O = 2-; Br= -1; H = +1
*(BrO)1- =hypobromite ion
e. As4
f. K2O2 : O = 1- (peroxide ion); K= 1+
Oxidation Numbers: 4.50
a.
b.
c.
d.
e.
f.
Oxidation Numbers: Assessment
Assign an oxidation number for each element in
the examples below:
1. H2
2. Cu
3. Fe2O3
4. N2O5
5. H(NO3)
6. CCl4
8. Cr(CO3)
9. OF2
10. Ca(OH)
Oxidation Numbers: Assessment
Assign an oxidation number for each element in
the examples below:
1. H2
2. Cu
3. Fe2O3
4. N2O5
5. H(NO3)
6. CCl4
8. Cr(CO3)
9. OF2
10. Ca(OH)
Chem II: Block 10.16.14
Due:
• Oxidation/Reduction Worksheet
Objectives:
• I can distinguish between oxidation and reduction
reactions using oxidations numbers.
• I can balance oxidation-reduction (Redox) reactions.
Redox Reactions
Ex.
2Ca + O2 -----> 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 + O2 -----> 2CaO
Half-Reactions: Separates/identifies the oxidized and
reduced reactions that occur simultaneously in
nature-why called Redox reactions.
Oxidized Reaction:
Reduced Reaction:
Chem II: Block 10.16.14
Due:
• Redox Reaction Worksheet
Objectives:
• I can distinguish between oxidation and reduction
reactions using oxidations numbers.
• I can balance oxidation-reduction (Redox) reactions.
Redox Reactions Practice Problems
1. Classify each half reaction as oxidation or reduction.
a. Ba ----> Ba2+ + 2eb. 2H1+ + 2e- -----> H2
2. Using oxidation numbers, predict if the reactions below
are redox reactions.
a. Fe (s) + Cu(SO4) (aq) ----> Fe(SO4) (aq) + Cu (s)
b. NaCl (aq) + Ag(NO3) (aq) ---> Na(NO3) (aq) + AgCl (s)
Redox Reactions
Chem II: Block 10.20.14
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I identify the redox half-reactions.
• I can balance redox reactions.
Balancing Redox Reactions: Acidic Solutions
Cu (s) + NO3- (aq) ----> Cu2+ (aq) + NO2 (g)
a. Validate this is a redox reaction by using oxidation
numbers to establish the half-reactions.
Balancing Redox Reactions: Acidic Solutions
Redox Reactions: Half Reactions
Gallery Walk
Redox Reactions Quiz
• Complete Redox Reaction Quiz
Chem II: Block 10.21.14
Infinite Campus:
• Redox Reaction Quiz (20pts.)
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I can identify redox half-reactions. (oxidation/reduction)
• I can balance redox reactions. (acidic/basic solutions)
Balancing Redox Reactions: Acidic Solutions
Cu (s) + NO3- (aq) ----> Cu2+ (aq) + NO2 (g)
Balancing Redox Reactions
• Assign oxidation numbers to identify half-reactions.
• Balance each half reaction with the following steps:
a. Balance all elements besides O and H.
b. Balance O by adding H2O molecules
c. Balance H atoms by adding H+ ions
d. Balance charge by adding electrons so that the
charge on each side is equal.
e. Make sure # of e- being lost = # of e- being gained.
f. Add the two half-reactions together and cross out
substances that appear on both sides.
Balancing Redox Reactions
• Assign oxidation numbers to identify half-reactions.
• Balance each half reaction with the following steps:
a. Balance all elements besides O and H.
b. Balance O by adding H2O molecules
c. Balance H atoms by adding H+ ions
d. Balance charge by adding electrons so that the
charge on each side is equal.
e. Make sure # of e- being lost = # of e- being gained.
f. Add the two half-reactions together and cross out
substances that appear on both sides.
Chem II: Block 10.22.14
Infinite Campus:
• Redox Reaction Quiz (20pts.)
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I can identify redox half-reactions. (oxidation/reduction)
• I can balance redox reactions. (acidic/basic solutions)
Redox Reactions: Gallery Walk
• Complete your redox reaction.
• Observe two other redox reactions, checking
your peers answer.
Balancing Redox Reactions: Acid
H2O2 + KMnO4 + H2SO4 --> Mn(SO4) + O2 + H2O
Redox Reactions
Redox Reactions
•
Ag(NO3) + 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
(Cr2O7)-2 (aq) + I- (aq)----> Cr3+ (aq) + (IO3 )- (aq)
Chem II: Block 10.23.14
Infinite Campus:
• Redox Reaction Quiz (20pts.)
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I can identify redox half-reactions. (oxidation/reduction)
• I can balance redox reactions. (acidic/basic solutions)
Balancing Redox Reactions: Basic
NO2- (aq) + Al(s) -----> NH3 (aq) + Al(OH)4- (aq)
Balancing Redox Reactions: Basic
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.
Balancing Redox Reactions: Acidic
(Cr2O7)-2 (aq) + I- (aq)----> Cr3+ (aq) + (IO3 )- (aq)
Chem II: Block 10.24.14
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I can identify redox half-reactions. (oxidation/reduction)
• I can balance redox reactions. (acidic/basic solutions)
(Redox Reaction Lab)
Homework:
• Complete post-lab qts.
Redox Reaction Lab
Redox Titration Lab
http://www.webassign.net
Redox Titration Lab
H2O2 + KMnO4 + H2(SO4)  Mn(SO4) + K2(SO4) + O2 + H2O
Pre-Lab:
1. Practice reading and working stopper on Buret.
(Measure out 15 mL of water 3xs from buret, validate
volume with graduated cylinder.
2. Complete pre-lab questions from lab
Chem II: Block 10.27.14
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I can identify redox half-reactions. (oxidation/reduction)
• I can balance redox reactions. (acidic/basic solutions)
(Redox Reaction Lab)
Homework:
• Complete post-lab qts.
Redox Reaction Lab
H2O2 + K(MnO4) + H2(SO4) --> Mn(SO4) + K2(SO4) + O2 + H2O
Oxidized Element: O
H2O2 -----> O2
Reduced Element: Mn
(MnO4)1- -----> Mn2+
Balanced Equation?
Redox Reaction Lab
• At least get two trials completed.
• Work on pre-lab qts. 5 and post-lab qts.
Chem II: Block 10.28.14
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I can identify redox half-reactions. (oxidation/reduction)
• I can balance redox reactions. (acidic/basic solutions)
(Redox Reaction Lab)
• I can apply stoichiometry to balanced chemical equations.
Homework:
• Stoichiometry Problems
Redox Reaction Lab
H2O2 + K(MnO4) + H2(SO4) --> Mn(SO4) + K2(SO4) + O2 + H2O
Oxidized Element: O
H2O2 -----> O2
Reduced Element: Mn
(MnO4)1- -----> Mn2+
Balanced Equation?
Chem II: Block 10.29.14
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I can identify redox half-reactions. (oxidation/reduction)
• I can balance redox reactions. (acidic/basic solutions)
(Redox Reaction Lab pre/post lab qts.)
• I can apply stoichiometry to balanced chemical equations.
(Apply to Redox Reactions)
Homework:
• Stoichiometry Problems
• Conclusion to Redox Lab
• Redox with Stoichiometry Exam-Friday
Redox Reaction Lab
Redox Reaction Lab: Due Thursday
• pre/post lab qts. complete
• Calculate percent error of H2O2 concentration
add to post-lab qts.
• Establish a conclusion-paragraph format
-addresses purpose of lab
-analysis and accuracy of your data/class’s data
-what did you learn from the lab
-modification(s) if could repeat lab
Redox Reaction Lab: Due Thursday
• pre/post lab qts. complete
• Calculate percent error of H2O2 concentration
add to post-lab qts.
• Establish a conclusion-paragraph format
-addresses purpose of lab
-analysis and accuracy of your data/class’s data
-what did you learn from the lab
-modification(s) if could repeat lab
Stoichiometry
Stoichiometry:
• Converting between substances in a balanced
chemical equation using mole conversions.
www.larapedia.com
Stoichiometry
www.larapedia.com
Redox Reactions: Stoichiometry Applications
2 H2O + NO2- + 2Al(s) ----> NH4+ + 2AlO2a. If we start with 3.8 moles of NO2- how
many moles of AlO2- could be produced?
b. If we want 13 grams of NH4+ ion, how many
grams of Al would we need to start with?
Redox Reactions: Percent Yield
2 H2O + NO2- + 2Al(s) ----> NH4+ + 2AlO2a. If we start with 3.8 moles of NO2- how many
moles of AlO2- could be produced?
If 7.0 moles AlO2- was actually produced in the lab,
what would the percent yield be?
b. If we want 13 grams of NH4+ ion, how many grams
of Al would we need to start with?
If 34.8 g of Al was actually produced in the lab, what
would the percent yield be?
Percent Yield
• Percent Yield: (Actual/Theoretical) x 100
Chem II: Block 10.30.14
Due:
• Stoichiometry Problems
Objectives:
• I can classify reactions as redox reactions using oxidations
numbers.
• I can identify redox half-reactions. (oxidation/reduction)
• I can balance redox reactions. (acidic/basic solutions)
(Redox Reaction Lab pre/post lab qts.)
• I can apply stoichiometry to balanced chemical equations.
(Apply to Redox Reactions)
Homework:
• Redox Reactions and Stoichiometry Review
Redox Titration Lab Results
Lab Group
1
2
3
4
5
Avg. volume
of KMnO4
% of H2O2 in
Solution (Avg.)
% Error
H2O2
Redox Reaction Lab: Extension Problem
H2O2 + K(MnO4) + H2(SO4) --> Mn(SO4) + K2(SO4) + O2 + H2O
Oxidized Element: O
H2O2 -----> O2
Reduced Element: Mn
(MnO4)1- -----> Mn2+
Balanced Equation?
Redox Reaction Lab: Extension of Lab
Stoichiometry Worksheet
Stoichiometry: Limiting Reactants
• Limiting Reactant:
• Excess Reactant:
en.wikipedia.org
Stoichiometry: Limiting Reactants
• Limiting Reactant: completely consumed
• Excess Reactant: partially consumed
en.wikipedia.org
Stoichiometry: Limiting Reactant
HCl + Mg -------> MgCl2 + H2
1. What type of reactions is this?
2. Balance equation if needed.
3. If 6.8 moles of Mg react with 7.5 moles of HCl which is
considered the limiting reactant? excess reactant?
Reactants
Have (moles) Need (moles)
Stoichiometry: Limiting Reactant
2HCl + Mg -------> MgCl2 + H2
1.If 6.8 moles of Mg react with 7.5 moles of HCl how
many moles of MgCl2 can be produced?
Reactants
Have (moles) Need (moles)
HCl (limited)
7.5 mol
13.6
Mg (excess)
6.8 mol
3.75