AP Chemistry
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Concepts
Details
Empirical
Definition
Formula &

Molecular
Formula

How is empirical formula calculated?
How is molecular formula calculated?
:
.
Ionic vs
A. Formula differences?
Covalent
compounds
B. Chemical differences?
Boiling points
Melting points
Conductivity
How does number of ions affect conductivity?
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Density
Definition:
Changes with changes in ___________________
Lattice
Definition:
Energy in
ionic
compounds
Coulombs Law:
Relationships:
Bond
Compare single – double – triple bond strength.
Energy in
Covalent
Compounds
How does this relate to bond length?
How can H be calculated for a reaction using bond energies?
Molarity
What is Molarity?
What will the final concentration KNO3 when 400 mL of 1.8 M Ba(NO3)2 solution reacts
with 300 mL of a 1.2 M K2SO4 solution?
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Gases
What variable affects:

Molecular speed

Density

Effusion
What is partial pressure?
STP?
When should it be used?
What is your go to equation for gases?
Electron
Configuratio
Write a sample electron configuration for the following:

A noble gas

A transition metal

A chemically unreactive element

An element with 1 valence electron in the p block

An element with an electron in an excited state.

A halogen

Two unpaired electrons
ns
How are valence electrons identified in an electron configuration?
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Periodic
All periodic trends are best explained by atomic radius, quantum levels, the effective
Trends
nuclear charge of the nucleus and the shielding of the core electrons.
Use these principles to explain:

The difference between 1st ionization energy for Potassium and Rubidium

The difference between 1st and 2nd ionization energy in sodium.

The difference in electron affinity between Bromine and Iodine.

When looking at sequential ionization energies for Aluminum (1 st, 2nd, 3rd, etc.)
Where would you expect to see a large increase? Why?
Molecular

Molecular shapes are relevant for ______________ bonded molecules.
Shapes

Examples:

Lewis Dot structures are key to determining molecular shapes.

After a Lewis dot structure is determined, the shape of the molecule can be
determined.

Polarity can also be determined by:
Look at VSEPR Shapes handout
Practice – For

CH4

BF3
each of the
following
molecules
determine
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AP Chemistry
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
Lewis Dot

TeF6

KrF4

SO2

IF3

SeF6

AsF5

KrF2

NH3

Sigma bond

Pi bond

Single

Double

Triple

Ionic Bonds

Hydrogen bonding
structure

Shape

Polarity

Hybridizati
on
Multiple bonds
Intermolecular
Forces
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Physical

Dipole dipole attractions

London dispersion

Rank the intermolecular forces in terms of strength.

How do IMF’s affect the boiling point of a liquid?

How do IMF’s affect the melting point of a liquid?

How do IMF’s affect the vapor pressure of a liquid?

What is Hvap of a chemical? How will this be affected by IMF’s?

Mole Fraction

Solubility – what does “like dissolves like” mean

Compare the boiling point of a solution to the boiling point of a pure solvent.
properties due
to
intermolecular
Forces
Solutions
Name the principle.

Compare the freezing point of a solution to the freezing point of a pure solvent.
Name the principle.
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AP Chemistry
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
Compare the vapor pressure of a solution to the vapor pressure of a pure solvent.

Van’t Hoff factor (i) How many particles are in the following
o
C6H12O6
o
NaCl
o
AlCl3
o
C2H5OH
How does this affect freezing point, boiling point and vapor pressure of a solution?
Kinetics

Kinetics involves the study of:

Reaction rate is determined by ____/____

What is the generic form for rate law?
Rate =

Rate law must be determined_______________.

For the following orders of reactions, indicate what doubling the concentration
does to the reaction rate.
o
0 order reactant
o
1st order reactant
o
2nd order reactant
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Differential rate law:
Integrated Rate Law:
Draw the graphs of straight lines for 0, 1st and 2nd order reactants, write the equations
to go with each graph.
Reaction

What is a reaction mechanism?
Mechanism

How can you tell if a chemical is a catalyst?

How can you tell if a chemical is an intermediate?

What are the two criteria that must be met to determine if a reaction
mechanism acceptable?
o
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o

How is a catalyst identified?

How in an intermediate identified?
The proposed mechanism for the reaction in this question is shown below:
Step 1: 2NO (g)--> N2O2 (g) (fast)
Step 2: N2O2 (g) + H2 (g) --> H2O2 (g) + N2 (g) (slow)
Step 3: H2 (g) + H2O2 (g) --> 2H2O (fast)
A) Write the balanced equation for this reaction.
B) Identify the rate-determining step.
C) Write a rate law that is most consistent with this mechanism
Equilibrium

What is activation energy?

Draw an energy profile for an exothermic rxn

Draw an energy profile for an endothermic rxn.

Show how a catalyst changes activation energy on each graph.

Kc –

Kp –

Properties of equilibrium-
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
What goes in the equilibrium expression?

What does the equilibrium expression tell you?
At a particular temperature K = 3.75 for the reaction:
SO2(g) + NO2(g) SO3(g) + NO(g)
All four gases had an initial concentration of 0.800 M, calculate the equilibrium
concentrations of the gases.
At a particular temperature, 12.0 mol of SO 3 is placed into a 3.0-L rigid container,
and the SO3 dissociates by the reaction:
2SO3 (g)  2SO2 (g) + O2 (g)
At equilibrium, 3.0 mol of SO2 is present. Calculate K for this reaction
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LeChatelier’s
Definintion:
Principle
How do the following affect equilibrium?

aq or gas added/removed?

Solid added/removed?

Unreactive gas added/ removed?

The volume of a container is increased/decreased?

Temperature is increased for an endothermic reaction? Exothermic reaction?
How is K changed?

Temperature is decreased for an endothermic reaction? Exothermic reaction?
How is K changed?
Acids and
Strong Acids:
Bases
Strong bases:
Examples of weak acids:
Examples of weak bases:

How is pH calculated?

pOH?

[H+] From pH

[OH-] from pOH
What is Kw?
Is the [H+] concentration 0 for a base?
Why or why not?

Strong acids _______________________.

pH is calculate by using _________________
Calculating
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AP Chemistry
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the pH of
For the following acids, calculate pH
strong acids
Calculating
the pH of

.004 M HCl

.05 HNO3

1.0 x 10-8 M HBr

Strong bases _______________________.

pH is calculate by using _________________
For the following bases, calculate pH

.015 M NaOH

.05 Ca(OH)2

1.0 x 10-8 M KOH

Weak acids do not _______________________

What is the acid dissociation constant? What does it tell you about an acid?

What is the pH of a 0.15 M solution of HC 2H3O2?

What concentration of HCN would you need to create a pH of 4.25? (K a = 6.2 x
strong bases
Calculating
the pH of
Ka=1.8 x 10-5
10-10)
weak acids

How do weak bases form hydroxide?

What is the base dissociation constant? What does it tell you about a base?

What is the pH of a 0.75 M solution of NH 3? Kb=1.8 x 10-5
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
Kb, the base dissociation constant, for a base is 9.4 x 10-4 at room temperature.
At this temperature, what is the approximate percent dissociation of the base in
a 1.0 M solution?
Calculating
the pH of
weak bases

A weak acids conjugate base will produce a basic salt.

A weak bases conjugate acid will produce an acidic salt.

__________________ is used to find Ka or Kb.
Identify the following salts as acidic, or neutral. For each salt, calculate the pH of the
solution.
Acid/Base

.600 M NH4Cl
Kb for NH3 = 1.8 x 10-5

1.2 M KNO3

.98 M NaC2H3O2 Ka for HC2H3O2 =1.8 x 10-5

What is a buffer?

Give two examples of acidic buffer systems.
properties of
salts
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
Give two examples of basic buffer systems.

What is the pH of an aqueous solution containing 0.20M acetic acid and 0.10M
Buffer
solutions
sodium acetate?

Ksp –

Molar solubility –

What information does Ksp give you?

What information does molar solubility give you?

Given Ksp ___________________ can be found

Given molar solubility _______________can be found
Solubility
Product
(Ksp)
Several reactions are carried out using AgBr, a cream colored silver salt for which the
value of the solubility-product constant,
Ksp, is 5.0 x 10-13 at 298K.
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AP Chemistry
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
Write the expression for the solubility–product constant, Ksp, of AgBr.

Calculate the value of [Ag+] in 50.0 mL of a saturated solution of AgBr at 298K.

A 50.0 mL sample of distilled water is added to the solution described in the
bullet above, which is in a beaker with some solid AgBr at the bottom. The
solution is stirred and equilibrium is reestablished. Some solid AgBr remains in
the beaker. Is the value of [Ag+] greater than, less than or equal to the value you
calculated in the part above? Justify your answer.

Calculate the minimum volume of distilled water, in liters, necessary to
completely dissolve a 5.0 g sample of AgBr(s) at 298 K. (The molar mass of AgBr
is 188g/mol.)
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
A student mixes 10.0 mL of 1.5 x 10-4 M AgNO3 with 2.0 mL of 5.0 s 10-4
M NaBr and stirs the resulting mixture. What will the student observe? Justify
your answer with calculations.

The color of another salt of silver, AgI(s), is yellow. A student adds a solution of
NaI to a test tube containing a small amount of solid, cream colored AgBr. After
stirring the contents of the test tube, the student observes that the solid in the
test tube changes color from cream to yellow.
Thermo-
o
Write a chemical equation for the reaction that occurred in the test tube
o
Which salt has a great Ksp: AgBr or AgI. Justify your answer.
Enthalpy (include units)–
dynamics

How can it be measured?

Specific heat –

What is the relationship between specific heat and change in temperature?

H + means

H – means

Hf-
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AP Chemistry
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
What is the Hf of elements?

How can the standard enthalpies of formation be used to solve for Hrxn?

Hcomb-
Find the H for the reaction below, given the following reactions and subsequent H
values:
2CO2(g) + H2O(g) --> C 2H2(g) + 5/2O2(g)
C2H2(g) + 2H2(g) --> C2H6(g)
H =-94.5 kJ
H2O(g) --> H2(g) + 1/2O2 (g)
H =71.2 kJ
C2H6(g) + 7/2O2(g) --> 2CO2(g) + 3H2O(g)
H =-283 kJ
Entropy (include units)-

S + means

S – means

When looking at a chemical reaction what do you look at to determine if entropy is
increasing or decreasing?

Free Energy (include units)
G + means

G – means

G 0 means
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AP Chemistry
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
Gibbs Free energy equation and Chart

Because G = 0 means the system is at equilibrium,
______________________ can be used to fine the equilibrium constant.
A student performs an experiment to determine the molar enthalpy of a solution of
urea, H2NCONH2. The student places 91.95 grams of water at 25C into a coffee-cup
calorimeter and immerses a thermometer into the water. After 50 s, the students
adds 5.13 grams of solid urea, also at 25, to the water and measures the
temperatures of the solution as the urea dissolves. A plot of the temperature data is
shown in the graph below.

Determine the change in temperature of the
solution that results from the
Dissolution of the urea.

According to the data, is the dissolution of urea in water an endothermic process
or an Exothermic process? Justify your answer.

Assume that the specific heat capacity of the calorimeter is negligible and that
the specific heat capacity of the solution of urea and water is 4.2 J/gC
throughout the experiment.
o
Calculate the heat of dissolution of the urea in joules.
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AP Chemistry
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o

Calculate the molar enthalpy of the solution, Hsoln, of urea in kJ/mol.
Using the information in the table below, calculate the value of the molar
entropy of solution, Ssoln, of urea at 298 K. Include units with your answer.

Hsoln urea
14.0 kJ/mol
Gsoln urea
-6.9 kJ/mol
The student repeats the experiment and this time obtains a result for Hsoln of
urea that is 11 percent below the accepted value. Calculate the value of Hsoln
that the student obtained in the second trial.

The student performs a third trial of the experiment but this time adds urea
that has been taken directly from a refrigerator at 5C. What effect, if any,
would using the cold urea instead of urea at 25C have on the experimentally
obtained value of Hsoln? Justify your answer.
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AP Chemistry
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Oxidation – Reduction
Electrochemist
ry

What is Oxidation?

What is Reduction?

What are the steps for balancing half reactions?

What are standard reduction potentials?

If substance is likely to be reduced, what does that mean about it’s potential
as an oxidizing agent? Where are these chemicals found on the standard
reduction potential chart?

If a substance is likely to be oxidized, what does that mean about it’s
potential to be a reducing agent? Where are these chemicals found on the
standard reduction potential chart?
Galvanic Cell
Draw a basic galvanic cell, with all parts labeled. Show electron flow.

How is cell potential found?

What is the relationship between G and Ecell?
20

What is a concentration cell?
AP Chemistry
AP Exam Review
The diagram below shows the experimental setup for a typical electrochemical
cell that contains two standard half-cells. The cell operates according to the
reaction represented by the following equation.
Zn(s) + Ni2+(aq)  Ni(s) + Zn2+(aq)

Identify M and M2+ in the diagram and specify the initial concentration
for M2+ in solution.

Indicate which of the metal electrodes is the cathode. Write the balances
equation for the reaction that occurs in the half-cell containing the
cathode.

What would be the effect on the cell voltage if the concentration of Zn 2+
was reduced to 0.100 M in the half cell containing the Zn electrode?

Describe what would happen to the cell voltage if the salt bridge was
removed. Explain.
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