Chem II:Gibbs Free Energy and Chemical Equilibrium
Infinite Campus Update:
• Thermochemistry Exam(24pts.)
• Gibbs Free Energy Textbook Problems (10pts.)
• Spontaneous Reaction Quiz (10pts.)
Objectives:
• Review Gibbs Free Energy Equation
•Review factors that influence speed of reactions.
•Determine what chemical equilibrium is for reversible reactions.
•Identify stresses that alter the chemical equilibrium position of a
system.
• Explain what the value of Keq indicates about the position of
equilibrium.
Gibbs Free Energy Equation
Complete Qts. 497 from textbook problems
• Explain whether or not this reaction increases
or decreases in entropy.
• Explain whether or not this reaction increases
or decrease in enthalpy
• Explain whether or not this reaction is
spontaneous or not.
Gibbs Free Energy Review
Chemical Reactions Rates
• Reaction Rates = how fast the reactants
chemically change into the products.
• Collision Theory: Reactant particles will form
products when reactants collide:
- at the right position.
- and exchange the right amount of kinetic energy.
Chemical Reaction Energy Diagram
Activation Energy:
•The amount of energy needed to chemically convert
reactants to products.
Rates of Chemical Reactions
What are factors that can affect speed of reactions?
Chem II: 4.14.15
Due:
• Gibbs Free Energy Textbook Problem s
Objectives:
•Review factors that influence speed of reactions.
•Determine what chemical equilibrium is for
reversible reactions.
•Identify stresses that alter the chemical equilibrium
position of a system.
Chemical Reaction Rate
1. Use the graph below to define what a chemical reaction rate is.
http://www.fccj.us/chm2046/SampleTest/46M10iAnswers.htm
http://www.fccj.us/chm2046/SampleTest/46M10iAnswers.htm
Rates of Chemical Reactions
2.Explain what you would do with each factor
below to increase the rate of a chemical reaction?
• Temperature
• Concentration of Reactants
• Surface Area of Reactants
• Catalysts
• Inhibitors
Catalysts
• Catalysts speed up reactions, but they are not
apart of the chemical reaction.
Ex. Enzymes keep your body temperature
around 37oC (98 oF) by speeding up important
biological reactions.
Catalyst and Energy Change
Inhibitors
• Inhibitors slow down a chemical reaction.
• Inhibitors bind to a catalyst and prevent it
from speeding up a reaction.
Ex. Preservation of food. Antioxidants prevent
foods from becoming stale or moldy.
Chem II: 4.15.15
Objectives:
•Review factors that influence speed of reactions.
•Determine what chemical equilibrium is for
reversible reactions.
•Identify stresses that alter the chemical equilibrium
position of a system.
Chemical Reactions
• Why is it that most chemical reactions do not
go to 100% completion?
Chemical Reactions
• Why is it that most chemical reactions do not go
to 100% completion?
• Most reactions are reversible.
• Reversible Reactions: The forward and reverse
reactions for a system occurs simultaneously.
• A double arrow is used in an equation that is
reversible.
Reversible Reactions
What does this graph tell you about reversible reactions?
http://www.800mainstreet.com/7/0007-000-ans-selftest.html
Chemical Reactions
• Why is it that most chemical reactions do not go
to 100% completion?
• Most reactions are reversible.
• Reversible Reactions: The forward and reverse
reactions for a system occurs simultaneously.
• A double arrow is used in an equation that is
reversible.
Chemical Equilibrium
•When the rates (speed) of the forward and reverse reactions
are equal to one another.
•Does it also mean the concentration of reactants and
products are equal?
http://www.800mainstreet.com/7/0007-000-ans-selftest.html
Chemical Equilibrium
Equilibrium Position:
•The concentration of reactants and products remain
constant.
•Indicates which direction is most favored. (forward)
Chemical Equilibrium
• What factors can affect chemical equilibrium?
Equilibrium Disturbance Chart
Equilibrium Disruption
Change in
pressure
Change in
temperature
Change in
concentration
System’s Response
(re-establish equilibrium)
Effects Equilibrium Constant
Chemical Equilibrium
A + B ---------> C + D
Chemical Equilibrium
• What factors can affect chemical equilibrium?
• LeChatelier’s Principle:
Chemical Equilibrium
• What factors can affect chemical equilibrium?
-Concentration of substances in the reversible
reaction.
-Temperature
-Pressure
• LeChatelier’s Principle:
-If a stress is exerted on system in equilibrium,
the system changes in a way to relieve that
stress.
-The equilibrium position will change.
Chem II: 4.16.15
Objectives:
•Review factors that influence speed of reactions.
•Determine what chemical equilibrium is for
reversible reactions.
•Identify stresses that alter the chemical equilibrium
position of a system.
•Explain (qualitatively/quantitatively) what the value
of Keq indicates about the position of equilibrium
Chemical Equilibrium: Bell Ringer
2. Use the graphs below to define chemical equilibrium.
Le Chatelier’s Principle: Application
Chem II: 4.21.15
Objectives:
•Review factors that influence speed of reactions.
•Identify stresses that alter the chemical equilibrium
position of a system.
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
Changes in Chemical Equilibrium
1. Using Le Chatelier’s Principle, explain how the
equilibrium position of this reaction is affected by
the following changes?
N2O4(g) + 58J
2NO2(g)
a. Addition of heat
b. Decrease in pressure
c. Addition of NO2
d. Removal of N2O4(g)
Changes in Chemical Equilibrium
1. Using Le Chatelier’s Principle, explain how the
equilibrium position of this reaction is affected by
the following changes?
N2O4(g) + 58J
2NO2(g)
a. Addition of heat
b. Decrease in pressure
c. Addition of NO2
d. Removal of N2O4(g)
Chemical Equilibrium Constant
• What is the chemical equilibrium constant
equation?
• What does the chemical equilibrium constant
value indicate about a reversible reaction at
equilibrium? Explain your answer with an
example.
Chem II: 4.22.15
Objectives:
•Review factors that influence speed of reactions.
•Identify stresses that alter the chemical equilibrium
position of a system.
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
Chemical Equilibrium Constant
• What is the chemical equilibrium constant
equation?
• What does the chemical equilibrium constant
value indicate about a reversible reaction at
equilibrium? Explain your answer with an
example.
Equilibrium Constants
• Ratio of product to reactant concentrations at
equilibrium, K(eq)
• Concentration expressed in molarity.
•
aA + bB
cC + dD
• Equilibrium constant identifies which reaction is
favored at equilibrium.
• Keq > 1:
• Keq <1:
Equilibrium Constants
• Ratio of product to reactant concentrations at
equilibrium, K(eq)
• Concentration expressed in molarity.
•
aA + bB
cC + dD
• Equilibrium constant identifies which reaction is
favored at equilibrium.
• Keq > 1: favors forward or products
• Keq <1: favors reverse or reactants
• No units for equilibrium constant
Chemical Equilibrium Constant
• What is the chemical equilibrium constant
equation?
• What does the chemical equilibrium constant
value indicate about a reversible reaction at
equilibrium? Explain your answer with an
example.
Calculating Chemical Equilibrium
A liter of a gas mixture at equilibrium at 10oC contains
0.0045mol of N2O4 and 0.030 mol of NO2.
N2O4 (g)
2NO2 (g)
a.Write the expression for the equilibrium constant for the
reaction above.
b. Calculate the equilibrium constant for the reaction.
c. Based on the Keq value, is the product or reactants favored
in this reversible reaction? Explain.
Chem II: 4.27.15
Infinite Campus:
• Le Chatelier’s Application-Gallery Walk
• Le Chatelier’s and Keq Quiz
Objectives:
•Identify stresses that alter the chemical equilibrium
position of a system. (Review)
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
Chem II: 4.28.15
Objectives:
•Identify stresses that alter the chemical equilibrium
position of a system. *Make-up Quiz Tomorrow, Wed.
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
•Interpret Ksp values. 
Chem II: 4.29.15
Objectives:
•Identify stresses that alter the chemical equilibrium
position of a system. Make-up Quiz
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
Chemical Equilibrium Calculations
R
I
C
E
R=ratio;
I=[Initial];
C=[change]; E= [at equilibrium]
Chemical Equilibrium
Chem II: 4.30.15
Infinite Campus:
Le Chat and Keq Make-up Quiz
Objectives:
•Identify stresses that alter the chemical equilibrium
position of a system.
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
Le Chatelier’s Quiz
Chemical Equilibrium Calculations
R
I
C
E
R=ratio;
I=[Initial];
C=[change]; E= [at equilibrium]
Chem II: 5.01.15
Due:
LeChat and Keq Packet
Objectives:
•Identify stresses that alter the chemical equilibrium
position of a system.
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
•Identify and apply Ksp constant.
Homework:
Exam next Wednesday-begin to review
Spontaneous Reactions and Equilibrium
Exam Concepts:
• Factors that influence the rate of a reaction
• Energy diagrams(activation eneryg/catalyst)
• Entropy vs. Enthalpy
• Classifying spontaneous reactions using Gibbs
Free Energy Equation.
• Chemical Equilibrium Constant, Keq
(interpret/apply)
• Le Chatelier’s Prinple (application)
• Solubility Equilibrium Constant, Ksp
(interpret/apply)
Spontaneous Reactions and Equilibrium
Exam Concepts:
• Factors that influence the rate of a reaction
• Energy diagrams(activation eneryg/catalyst)
• Entropy vs. Enthalpy
• Classifying spontaneous reactions using Gibbs
Free Energy Equation.
• Chemical Equilibrium Constant, Keq
(interpret/apply)
• Le Chatelier’s Prinple (application)
• Solubility Equilibrium Constant, Ksp
(interpret/apply)
Chemical Equilibrium Calculations
Worksheet #2
R
I
C
E
R=ratio;
I=[Initial];
C=[change]; E= [at equilibrium]
Chem II: 5.05.15
Due:
• Infinite Campus updated
• LeChat and Keq Packet-due today
Objectives:
•Identify stresses that alter the chemical equilibrium
position of a system.
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
•Identify and apply Ksp constant.
Homework:
• Exam on Wednesday
Solubility Equilibrium Constant
1. What does the solubility equilibrium constant
represent, K(sp).
2. What is the K(sp) equation?
3. What factor(s) influence the K(sp) value?
Solubility Equilibrium
•
Also called solubility equilibrium product, K(sp) :
the product of the ions’ concentration values
• K(sp) expression:
• Dependent upon temperature
• Determines the degree of solubility
for the compound.
Chem II: 5.05.15
Due:
• LeChat and Keq Packet-LATE
Objectives:
•Identify stresses that alter the chemical equilibrium
position of a system. Le Chat Lab(Tues./Wed.)
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
•Identify and apply Ksp constant. (Tues.)
Homework:
• Exam on Thursday
Solubility Equilibrium
•
Also called solubility equilibrium product, K(sp) :
the product of the ions’ concentration values
• K(sp) expression:
• Dependent upon temperature
• Determines the degree of solubility
for the compound.
Solubility Equilibrium Constant, Ksp
1.
a.
b.
c.
Rank these solutions from least to most soluble(@25oC)
Pb(SO4), Ksp: 6.3x10-7
Zn(OH), Ksp: 3.0x10-16
Ca(SO4), Ksp: 2.4x10-5
2.What is the concentration of lead ions and chromate ions in a
saturated lead chromate,Pb(CrO4) solution at 25oC?
Ksp(PbCrO4) = 1.8x10-14
3. What is the concentration of magnesium ions and hydroxide ions in a
saturated magnesium hydroxide solution, Mg(OH)2?
KspMg(OH)2 =7.1x10-12
Solubility Equilibrium Constant, Ksp
1.
a.
b.
c.
Rank these solutions from least to most soluble(@25oC)
Pb(SO4), Ksp: 6.3x10-7
Zn(OH), Ksp: 3.0x10-16
Ca(SO4), Ksp: 2.4x10-5
2.What is the concentration of lead ions and chromate ions in a
saturated lead chromate,Pb(CrO4) solution at 25oC?
Ksp(PbCrO4) = 1.8x10-14
3. What is the concentration of magnesium ions and hydroxide ions in a
saturated magnesium hydroxide solution, Mg(OH)2?
KspMg(OH)2 =7.1x10-12
Le Chatelier’s Principle Lab
Purpose:
Hypothesis:
1. Predict how the system will react to the
stresses applied to test tubes #2-4.
2. What is the purpose of the control(test tube
number one) in this experiment?
Le Chatelier’s Principle Lab
Purpose:
Hypothesis:
1. Predict how the system will react to the
stresses applied to test tubes #2-4.
2. What is the purpose of the control(test tube
number one) in this experiment?
Chem II: 5.11.15
Due:
• Le Chat Lab-13 pts.
Objectives:
•Identify stresses that alter the chemical equilibrium
position of a system.
•Determine what the chemical equilibrium is for
reversible reactions(qualitatively/quantitatively).
•Identify and apply Ksp constant.
Homework:
• Exam on Wednesday
Le Chat Lab
Chem II: Reaction Rates and Equilibrium
(11.14)
Objectives:
•Review factors that influence speed of reactions.
•Determine what chemical equilibrium is for reversible
reactions.
•Identify stresses that alter the chemical equilibrium
position of a system.
• Explain (qualitatively/quantitatively) what the value of
Keq indicates about the position of equilibrium
•Interpret solubility equilibrium.
Equilibrium Disturbance: Pressure
N2O4(g) + 58J ---> 2NO2(g)
apchem09.wikispaces.com
Changes in Chemical Equilibrium
1. Using Le Chatelier’s Principle, explain how the
equilibrium position of this reaction is affected by
the following changes?
N2O4(g) + 58J
2NO2(g)
a. Addition of heat
b. Decrease in pressure
c. Addition of NO2
d. Removal of N2O4(g)
2. Can a pressure change shift the equilibrium position
in every reversible reaction? Explain your answer.
3. a. What is a chemical equilibrium constant?
b. What can it tell you about a reversible reaction?
Calculating Chemical Equilibrium Constants
7. The reversible reaction: N2(g) + 3H2(g) -----> 2NH3(g)
produces ammonia which is a fertilizer. At equilibrium, a 1-L
flask contains 0.15 mol H2, 0.25 mol N2, and 0.10molNH3.
a. Write the expression for the equilibrium constant for the
reaction?
b. Calculate the Keq for the reaction.
c. Based on the Keq value, is the product or reactants favored
in this reversible reaction? Explain.
Calculations with Chemical
Equilibrium Constants
• Gallery Walk of Homework Questions.
Extra practice problems: 16., 51., 52.
Chem II: Reaction Rates and Equilibrium
(11.15)
Objectives:
•Review factors that influence speed of reactions.
•Determine what chemical equilibrium is for reversible
reactions.
•Identify stresses that alter the chemical equilibrium
position of a system.
• Explain (qualitatively/quantitatively) what the value of
Keq indicates about the position of equilibrium
•Interpret solubility equilibrium.
Chem II: Reaction Rates and Equilibrium (11.16)
Infinite Campus Update:
• Chemical Equilibrium Quiz
Objectives:
•Review factors that influence speed of reactions.
•Determine what chemical equilibrium is for reversible
reactions.
•Identify stresses that alter the chemical equilibrium position
of a system.
• Explain (qualitatively/quantitatively) what the value of Keq
indicates about the position of equilibrium
•Interpret solubility equilibrium constant.
•Interpreting rate laws and predicting reaction orders.
Reversible Reactions
Can you think of a reaction that is not reversible?
Reversible Reactions
Can you think of a reaction that is not reversible?
1. Formation of a gas if produced in an open
container.
2. Formation of insoluble or slightly soluble
products.
NaCl (aq) + AgNO3(aq) -----> NaNO3 (aq) + AgCl(s)
Solubility Equilibrium
1. What is the solubility equilibrium constant?
2. What does the solubility equilibrium
constant tell you?
3. Why does doctors give patients barium
sulfate solution for X-ray analysis when the
ions are toxic to our blood stream?
Solubility Equilibrium
•
Also called solubility equilibrium product, K(sp) :
the product of the ions’ concentration values
• K(sp) expression:
• Dependent upon temperature
• Determines the degree of solubility
for the compound.
Solubility Equilibrium Calculations
Ex. What is the concentration of barium ions and sulfate ions
in a saturated barium sulfate solution at 25oC.
a. Write out the solubility equation for barium sulfate.
b. What is the Ksp expression for barium sulfate solution?
c. What is the Ksp constant for barium sulfate solution at
25oC. Pg. 562
Chem II: Reaction Rates and Equilibrium (11.19)
Infinite Campus Update:
• Chemical Equilibrium Quiz
• Soda Can Lab Report (29pts.)
• Heats of Reaction Report (15pts.)
Objectives:
•Interpret solubility equilibrium constant.
•Interpreting rate laws and predicting reaction orders.
Solubility Equilibrium Calculations
• Practice problems: 18.3, 17, 18 (pg. 562)
Common Ion Effect
PbCrO4 (s) ---> Pb2+ (aq) + CrO42- (aq), Ksp = 1.8x10-14
What would happen if you add Pb(NO3)2 to the
solution at equilibrium?
Common Ion Effect
• Common ions: each salt in the solution has a
common (the same) ion.
• Common ion effect: Solubility is lowered for
one of the salts in the solution.
Ex. Adding sodium sulfate to barium sulfate
solution further decreases the solubility of
barium sulfate in solution.
Common Ion Effect
Ex. The solubility product constant of AgBr is
5.0x10-13. What is the bromide-ion concentration of a
1.00L saturated solution of AgBr to which 0.020 mol
of Ag(NO3) is added?
Solubility Equilibrium Calculations
Predicting Solubility: Double Replacement Reactions
• Can predict the solubility of substances produced
from a double replacement reaction.
Ex. Will barium sulfate precipitate when 0.5 L of 0.002M
Ba(NO3)2 reacts with 0.50 L of 0.008 M Na2(SO4) to form a
1L solution? The Ksp of Ba(SO4) is 1.1x10-10.
Predicting Solubility
• Predict whether calcium carbonate will precipitate
when 0.5 L of 0.001M Ca(NO3)2 is mixed with 0.5 L
of 0.008M Na2(CO3) to form 1L of solution. The Ksp
of CaCO3 is 4.5x10-9.
Chem II: Reaction Rates and Equilibrium (11.19)
Objectives:
•Interpret solubility equilibrium constant.
•Quiz over solubility equilibrium problems
•Predicting solubility of products from a double replacement
reaction.
•Interpreting rate laws and predicting reaction orders.
Additional Practice Problems
Predicting Solubility:
Questions 6 and 7:
Predicting Solubility
Practice Problems Key
10. Yes, AgCl because product of ions=
1.0x10-4 > Ksp of AgCl = 8.3x10-17.
11.Yes, CaCO3 product of ions= 2x10-7 > Ksp of
CaCO3 = 4.5x10-9
Chem II: Reaction Rates and Equilibrium (11.25)
Objectives:
•Review factors that influence speed of reactions.
•Determine what chemical equilibrium is for reversible
reactions.
•Identify stresses that alter the chemical equilibrium position
of a system.
• Explain (qualitatively/quantitatively) what the value of Keq
indicates about the position of equilibrium
•Interpret solubility equilibrium constant.
Predicting Solubility: Double Replacement Reactions
6a. Predict whether a precipitate will form in the
solution?
a. Ba2+= 0.02M, F1- = 0.0015M; actual Ksp= 1.0x10-6
Gallery Walk: Reaction Rates and Equlibrium
Lab Bench
Practice Problem Question
1
#2
2
#4
3
#5
4
#7
5
qts. on bench
6
qts. on bench
Gallery Walk: Reaction Rates and Equlibrium
Lab Bench
Practice Problem Question
1
#2
2
#4
3
#5
4
#7
5
qts. on bench
6
qts. on bench
Chemistry II: Foods Day
Name
Food
Name
Food
Chemistry II: 12.2
Objectives:
• Schedule make-up exams for this week.
• Interpreting rate laws and predicting reaction
orders.
Homework:
Rate Law Problems
Chemical Reaction Rates
Rate Law
• An expression that connects reaction rates
with concentration of reactants.
A + B ----->AB
• R = k [A]n[B]m
Rate Law Constant (k)
• R = k [A]n[B]m
• What is the rate law constant (k) dependent upon?
Reaction Orders
•
•
•
•
Exponents in the rate law expression.
R = k [A]n[B]m
Each reactant has an exponent.
It identifies a possible relationship between a
reactant’s concentration and the reaction rate.
• Order of Reaction = sum of orders in reaction (n+m)
Reaction Orders
• Exponents are small integers in the rate law expression.
• R = k [A]n [B]m
• Reaction orders are NOT coefficients from a balanced
equation.
• Determined only from experimental data.
[A]0 = rate change does not depend upon concentration
change of reactant.
[A]1 = rate change is directly proportional to concentration
change of reactant.
[A]2 = rate change is directly proportional to the square of
the concentration change of reactant.
[A]3 = rate change is directly proportional to the cube of the
concentration change of the reactant.
Rate Law Expressions
Rate Law
Three experiments that have identical conditions were
performed to measure the initial rate of the reaction.
2HI(g) ----> H2(g) + I2(g)
Experimental Results:
Experiment
[HI] Molar
Rate (M/s)
1
0.015
1.1x10-3
2
0.030
4.4x10-3
3
0.045
9.9x10-3
a. Write the rate law for this reaction.
Rate Law
Three experiments that have identical conditions were
performed to measure the initial rate of the reaction.
2HI(g) ----> H2(g) + I2(g)
Experimental Results:
Experiment
[HI] Molar
Rate (M/s)
1
0.015
1.1x10-3
2
0.030
4.4x10-3
3
0.045
9.9x10-3
b. Use the rate law expression to calculate the rate
constant for this reaction.
Chemistry II: 12.3
Objectives:
• Establishing and interpreting rate laws by predicting
reaction orders of reactants.
Homework:
• Rate Law problems
• Rate Law Lab: Read and complete pre-lab questions
Chemistry II: Rate Laws
1. a. What is a rate law?
2.
a.
b.
c.
3.
b. How is it useful to chemists?
A + B -----> C
Write the rate law expression for this reaction.
From experimental data, it was observed that as [A]
doubles the reaction rate doubles. As[B] doubles the
reaction rate does not change. Determine the order of
each reactant and add it to your rate expression above.
What is the overall reaction order for this reaction?
a. Identify a factor that affects the rate constant, k.
b. Identify a factor that does NOT affect the rate
constant,k.
Rate Law Practice Problems
Rate Law Calculations
Three experiments were performed to measure the initial rate
of the reactions.
A + B -----> C
Experimental Results: Only concentrations varied with each
[B] Molar
Rate (M/s)
experiment Experiment [A] Molar
a.
b.
c.
d.
e.
f.
1
1.2
2.4
8.0x10-8
2
1.2
1.2
4.0x10-8
3
3.6
2.4
7.2x10-7
What units are associated with concentration?
What units are associated with reaction rate?
Determine the reaction order for each reactant.
What is the overall order for this reaction?
Write the rate law expression for this reaction.
Calculate the rate constant,k, for this reaction.
Rate Law
Three experiments were performed to measure the initial rate
of the reactions.
A + B -----> C
Experimental Results: Only concentrations varied with each
[B] Molar
Rate (M/s)
experiment Experiment [A] Molar
1
1.2
2.4
8.0x10-8
2
1.2
1.2
4.0x10-8
3
3.6
2.4
7.2x10-7
Chemistry II: 12.4
Due:
Rate Law Practice Problems Worksheet
Objectives:
• Establishing and interpreting rate laws by predicting
reaction orders of reactants.
• Set-up Rate Law Lab
Homework:
• Rate Law Quiz tomorrow-review notes/practice
problems
• Be prepared for Rate Law Lab
Rate Law Problems: Gallery Walk
• Gallery walk designed to promote peer
collaboration and feed-back.
• Write your group’s answer on white board.
• Transfer your answer to the paper-will collect as
evidence of your participation in walk.
• Will rotate twice so that you can assess two other
group’s problems.
• Record your answer for those problems as well on
paper that will be collected.
Chemistry II: 12.5
Objectives:
• Establishing and interpreting rate laws by predicting
reaction orders of reactants.
• Rate Law Quiz
• Complete Rate Law Lab
Homework:
• Complete post-lab questions and work on lab
report.
Rate Law Lab
1. Review background and procedure sections from
modified version.
2. Complete pre-lab questions. Show work for one
experiment.
3. Lab Groups:
• Collect and ensure lab equipment is clean.
• Discuss pre-lab answers.
• Complete lab-follow modified version
• Complete post-lab questions
4. Work on Lab Report-Due Monday
Rate Law Lab
Materials Modification:
• watch glass instead of reaction plates
• Refer to each trial as an experiment instead of
well #, because NOT using reaction plates.
• small graduated cylinders instead of syringes.
• plastic pipettes
• paper towels instead of cotton swabs
Chemistry II: 12.5
Objectives:
• Establishing and interpreting rate laws by predicting
reaction orders of reactants.
• Complete Rate Law Lab
Homework:
• Complete post-lab questions and work on lab
report.
Chemistry II: 12.9
Infinite Campus Update:
• Chemical Reaction Rate/Equilibrium Exam (39pts.)
• Rate Law Gallery Walk (6pts.)
• Interpreting Rate Law Graph (10pts.)
• Rate Law Quiz (16pts.)
Objectives:
• Establishing and interpreting rate laws by predicting
reaction orders of reactants.
• Complete Rate Law Lab
Homework:
• Post Lab questions and Lab Report-due Wed.
• Check Infinite Campus for missing assignments.
Chemistry II: 12.10
Objectives:
• Establishing and interpreting rate laws by predicting
reaction orders of reactants.
• Analyze Rate Law Lab data
• Distinguishing between three definitions of Acids/Bases
Homework:
• Rate Law Lab Report-due Wed.
Rate Law Lab Data
Lab Group
Rate Order
Na2(S2O3)
Rate Order
HCl
Rate Law Lab Report
Your lab report needs to include the following headings:
• Purpose: brief summary-paragraph
• Materials: bullet of materials/stock solutions
• No hypothesis with this lab
• Data: Qualitative (paragraph) and Quantitative (tables)
• Analysis: (paragraph format)
• Conclusion: (paragraph format)
Rate Law Lab: Interpreting Data
• Think about what two experiments would yield the
most accurate reaction order for each reactant.
• Can repeat experiments if reaction order is not
obvious.
• Can validate reaction orde by graphing
concentration of each reactant vs. time.
Validate Reaction Order of Reactants
• [A] versus t (linear for a zero order reaction)
• ln [A] versus t (linear for a 1st order reaction)
• 1 / [A] versus t (linear for a 2nd order reaction)
http://www.chem.purdue.edu/gchelp/howtosolveit/Kinetics/IntegratedRateLaws.html
Rate Law Quiz
Chemical Equilibrium Exam
• Make-up Exam Date
Acids/Bases
Chpt. 15 (purple textbook)
• Acid/Base compounds have been defined
three ways.
a. Identify and distinguish between the three
definitions of acids/bases.
b. Identify and explain which definition is best
for chemist.
Chemistry II: 12.11
Objectives:
• Identifying the three definitions of acids and bases.
Homework:
• Rate Law Lab Report-due Thursday
• Organizing notes, unit exams, and quizzes for final next
week. Study guide will be issued tomorrow.
Homework Check-up: Defining Acids and Bases
1. Use your homework to define/illustrate the
following:
a. Arrhenius Acids and Bases
b. Bronsted-Lowery Acids and Bases
c. Lewis Acids and Bases
Acids and Bases
Arrhenius Acids and Bases:
Acids and Bases
Arrhenius Acids and Bases:
• Acids: Compounds that give off H+ ions in
aqueous solutions.
• Bases: Compounds that give off OH- ions in
aqueous solutions.
Acids and Bases: pH scale
Strong vs Weak Acids and Bases
Strong Acids/Bases: Dissociates 100% in solution.
Wead Acids/Bases: Dissocates less than 5% in solution.
Weak Acid: HNO2
Strong Acid: HCl
www.chem.wisc.edu
Strong vs. Weak Acids
Acid: Chemical Formula
Solubility in Water
hydrochloric: HCl
high
sulfuric: H2(SO4)
high
Phosphoric: H3(PO4)
low
Nitric : H(NO3)
high
Carbonic: H2(CO3)
low
Strong or Weak Acid
• The degree of dissociation or solubility is based on
how polar the chemical bond is between hydrogen
and the other substance.
• If bonded to a very electronegative element or
substance then it will dissociate easily in water.
• Ex. H----Cl
vs.
H-----(NO3)
Dissociation of HCl in water
en.wikipedia.org
Molecules and Polarity
Polar Molecules: Do not share electrons equally because
one element has a greater pull on electrons making up
bond.
Ex. O----H (between different non-metals)
Non-Polar Molecules: Share electrons equally because
each element has same pull on bonded electrons.
Ex. H-----H (Diatomic molecules. )
Electronegativity: “pull” on bonded electrons
Dissociation of HCl in water
en.wikipedia.org
Strong vs. Weak Bases
Bases
Solubility
K(OH)
high
Na(OH)
high
Ca(OH)2
high
Mg(OH)2
low
Strong vs. Weak Bases
• Metals degree of reactivity with water determines its
solubility and strength.
• Metals from group one are most reactive (most
soluble) with water, so are the strongest bases.
Defining Acids and Bases
Bronsted-Lowery Acids and Bases:
Defining Acids and Bases
Bronsted-Lowery Acids and Bases:
• Acids: Hydrogen ion donor
• Base: Hydrogen ion acceptor
Example: Ammonia (NH3) is classified as a base
when dissolved in water, why?
Defining Acids and Bases
Bronsted-Lowery Acids and Bases:
• Acids: Hydrogen ion donor
• Base: Hydrogen ion acceptor
Example 1: Ammonia (NH3) is classified as a base
when dissolved in water, why?
NH3(aq) + H2O (l) ----> NH4 (aq) + OH- (aq)
(base)
(acid)
(conjugate acid)
(conjugate base)
Conjugate Acid-Base Pair
Bronsted-Lowery Acids and Bases:
• Acids: Hydrogen ion donor
• Base: Hydrogen ion acceptor
*With reversible reactions identified conjugate
acid-base pairs.
*Conjugate acid-base pairs: Two substances in a
reversible reaction that are related to one another
by the loss or gain of a H+ ion.
NH3(aq) + H2O (l) ----> NH4 (aq) + OH- (aq)
(base)
(acid)
(conjugate acid)
(conjugate base)
Conjugate Acid-Base Pair
Bronsted-Lowery Acids and Bases:
• Acids: Hydrogen ion donor
• Base: Hydrogen ion acceptor
*With reversible reactions identified conjugate
acid-base pairs.
Example2: HCl is an acid when dissolved in water,
why?
Conjugate Acid-Base Pair
What is interesting about water in our BronstedLowery Acid/Base examples below?
Ex.1:
NH3(aq) + H2O (l) ----> NH4 (aq) + OH- (aq)
(base)
(acid)
(conjugate acid)
(conjugate base)
Ex.2:
HCl(aq) + H2O (l) ----> Cl- (aq) + H3O+ (aq)
(acid)
(base)
(conjugate base)
(conjugate acid)
Defining Acids/Bases
Lewis Acids and Bases:
Defining Acids/Bases
Lewis Acids and Bases:
• Lewis Acid: Accepts a pair of electrons during
covalent bonding.
• Lewis Base: Donates a pair of electrons during
covalent bonding.
Example:
Chemistry II: 12.12
Objectives:
• Scholastic Reading Inventory (SRI) Assessment
• Identifying and applying the three definitions of acids and
bases.
• I can assess the strength of an acid or base using the acid
dissociation constant.
Homework:
• Rate Law Lab Report-due Thursday
• Organizing notes, unit exams, and quizzes for final next
week. Study guide will be issued tomorrow.
Defining Acids/Bases
Lewis Acids and Bases:
• Lewis Acid: Accepts a pair of electrons during
covalent bonding.
• Lewis Base: Donates a pair of electrons during
covalent bonding.
Example:
Chemistry II: 12.13
Objectives:
• Identifying and applying the three definitions of acids and
bases.
• I can assess the strength of an acid or base using the acid
dissociation constant.
Homework:
• Rate Law Lab Report-due Today
• Organizing notes, unit exams, and quizzes for final next
week. Study guide will be issued tomorrow.
ChemII: 12.16.13
Due:
• Rate Law Lab: -late but will accept for partial credit.
Objectives:
• Identifying and applying the three definitions of acids and
bases.
• I can assess the strength of an acid or base qualitatively.
• Review for Final Exam
Homework:
• Organize unit exams, review study guide and notes.
• Power points are on my webpage.
• Study guide session available after school tomorrow.
• Check infinite campus for missing work, etc.
Defining Acids/Bases
Acid/Base Theories
Acid
Base
Arrhenius
H+ producer
OH- producer
Bronsted-Lowry
H+ donor
H+ acceptor
Lewis
Electron-pair acceptor
Electron-pair donor
Lewis Acids and Bases
Acid/Base Text Problems
Strength of Acids and Bases
ChemII: 12.17.13
Due:
• Rate Law Lab: -late but will accept for partial credit.
Objectives:
• Identifying and applying the three definitions of acids and
bases.
• I can assess the strength of an acid or base qualitatively.
• Review for Final Exam
Homework:
• Organize unit exams, review study guide and notes.
• Power points are on my webpage.
• Study guide session available after school tomorrow.
• Check infinite campus for missing work, etc.
Strength of Acids and Bases
• Is the strength of an acid/base dependent
upon concentration of solute or dissociation
of solute? Explain.
Acid/Base Equilibrium Expression
• Concentration ratio of products vs. reactants
Example:
Keq =
• If Keq is large, will it be a strong or weak acid/base?
• If Keq is small, will it be a strong or weak acid/base?
Final Exam Study Guide
Equilibrium Expression
In diluted solutions, H2O is constant and not apart of
the expression.
• Concentration ratio of the products to acid/base
reactant.
• Example of an Acid
CH3COOH (aq) + H2O(l) ---> CH3COO- (aq) + H3O+ (aq)
• Example of a Base:
NH3(aq) + H2O (l) ----> NH4 (aq) + OH- (aq)
Weak Acids: Dissociation Constants
• For weak acids, can use experimental data to calculate
the dissociation constant.
Ex. A 0.100M solution of ethanoic acid is only partially
ionized. From measurements of the pH of the solution [H+]
is determined to be 1.34x10-3 M. What is the acid
dissociation constant, Ka, of ethanoic acid.