AP Chemistry Torok

Big Idea 1

Chapters in textbook: 1-3, 6.8-6.9, 7

Pages in review book: 1-44, 93-112, 113-130

Topics

·  Empirical and molecular formulas

·  Limiting reactants

·  Electron configuration and orbital notation

·  Periodic trends (general and complex)

Practice problems in review book: pg 39-41(all MC and the 1 FR), pg 106 (MC 3-5), pg 125-126 (all MC and FR #1)

Example review problems:

1.  What is the empirical formula of a compound containing 68.4% Cr and 31.6% Oxygen? The molar mass of this compound is 304 g/mol. What is the molecular formula for this compound?

2.  255g of octane and 1510g of oxygen gas are present at the beginning of the reaction that goes to completion and forms carbon dioxide and water, 2C8H18 + 25O2 à 16CO2 + 18H2O.

  1. What is the limiting reactant?
  1. How many grams of water are formed?
  1. How many grams of excess reactant is consumed?
  1. How much excess reactant is left over?

3.  Write the electron configuration and orbital notation for Ga.

4.  Write examples of a violation of Hund’s rule, violation of Pauli Exclusion Principle, and an element in an excited state.

5.  General Periodic Trends

  1. Why does the atomic radius of atoms decrease as you move left to right on the periodic table? Bottom to top?
  1. Explain why ionization energy increases as you move across and up the periodic table.

6.  Complex Periodic Trends

  1. Which ion has a larger radius, Mg+2 or O-2? Why?
  1. Why does boron have a slightly lower first ionization energy than beryllium?
  1. Determine the element from the ionization energies (kj/mol) listed below:

1st / 2nd / 3rd / 4th / 5th
580 / 1,815 / 2,740 / 11,600 / 14,800

a)  Na b) Mg c) Al d) Si e) P

Big Idea 2

Chapters in textbook: 8-10

Pages in review book: 131-188

Topics

AP Chemistry Torok

·  Lewis dot structures

·  Octet rule + exceptions

·  Resonance

·  Shapes!!

·  Polarity

·  Combine gas law

·  Ideal gas law

·  Partial pressure

·  Graham’s law of effussion

AP Chemistry Torok

Practice problems in review book: pg 143-145 (all MC and all FR), pg 160-162 (all MC and all FR), pg 181-184 (all MC and all FR)

Example review problems:

1.  Use simple structure and bonding models to justify the following statements:

a.  Explain why atoms of second row elements such as N and O cannot have expanded octets, but those of third row elements such as P and S can.

b.  Discuss the differences in length of bond, strength of bond, and the type of bonds in the following molecules: CO2, H2S, and NO3.

2.  For each of the following:

a.  draw the molecular geometry of the molecule;

b.  state the molecular geometry of the molecule;

c.  determine if the molecule is polar or non-polar;

d.  include bond angle(s).

CO2 ClF3 SF4 CCl4

3.  A student collected a sample of hydrogen gas by the displacement of water as shown by the diagram above. The relevant data are given in the following table.

GAS SAMPLE DATA
Volume of sample / 90.0 mL
Temperature / 25 ºC
Atmospheric Pressure / 745 mm Hg
Equilibrium Vapor Pressure of H2O (25°C) / 23.8 mm Hg

a.  Calculate the number of moles of hydrogen gas collected.

b.  Calculate the number of molecules of water vapor in the sample of gas.

c.  Calculate the ratio of the average speed of the hydrogen molecules to the average speed of the water vapor molecules in the sample.

d.  Which of the two gases, H2 or H2O, deviates more from ideal behavior? Explain your answer.

Big Idea 3

Chapters in textbook: 4, 13.1, 13.4, 16.5, 20

Pages in review book: 45-70, 223-238, 349-375

Topics

AP Chemistry Torok

·  Oxidation Reduction reactions

·  M1V1=M2V2

·  Titrations

·  Neutralization reactions

·  Solubility rules

·  Balancing redox reactions

·  Voltaic cells

·  Cell Potentials

·  Free energy and redox

·  Electrolysis

AP Chemistry Torok

Practice problems in review book: pg 64 (MC 1-2, 5-7 and FR #1), pg 368 (all MC and all FR)

Example review problems:

1.  Answer the following questions about electrochemistry.

  1. Several different electrochemical cells can be constructed using the materials shown below. Write the balanced net-ionic equation for the reaction that occurs in the cell that would have the greatest positive value of Ecello.

  1. Calculate the standard cell potential, Ecello, for the reaction written in part a.

  1. A cell is constructed based on the reaction in part a above. Label the following on the picture below:
  2. metal used for the anode
  3. metal used for the cathode
  4. the amount and direction of electron flow through the wire.
  1. How would the voltage of the cell be affected if the salt bridge was removed? Justify your answer.
  1. Of the compounds, NaOH, CuS, and NaNO3, which one is appropriate to use in a salt bridge? Briefly explain your answer, and for each of the other compounds, include a reason why it is not appropriate.

2.  To solution 1 (2.00 L of 0.445 M HCl), you add 3.88 L of solution 2 (an unknown concentration of HCl). The resulting solution is 0.974 M. Assuming the volumes are additive, calculate the molarity of solution 2.

3.  Using solution 2 from above, if you add 250 mL of 1.0 M NaOH to 125 mL of solution 2, will the solution be acidic, basic, or neutral? Justify your answers by showing all your work.

Big Idea 6

Chapters in textbook: 15, 16, 17

Pages in review book: 261-328

Topics

AP Chemistry Torok

·  Equilibrium Constant

·  K vs. Q

·  Le Chatelier’s Principle

·  Strong vs. Weak A/B

·  Conjugate A/B

·  Ka x Kb = Kw = 1.0 x 10-14

·  pH= -log[H+]

·  pOH= -log[OH-]

·  pH + pOH = 14

·  5% rule

·  Common Ion effect

·  Buffers

·  A/B titration

·  Equivalence point

·  Titration curve

·  Half equiv. point at pKa

·  pH= pKa + log ([base]/[acid])

·  Solubility product constant

AP Chemistry Torok

Practice problems in review book: pg 271 (ALL MC and FR), pg 298 (ALL MC and FR), pg 321 (ALL MC and FR)

Example review problems:

Answer the following question:

  1. What is the pH of a 0.75M solution of ammonia? (Kb=1.8 x 10-5)
  1. What is the pH of a solution made by mixing 1.0L of 0.11M HCl with 3.0L of 0.080M NaF? (HF’s Ka=6.8 x 10-4)

3.  Calculate the molarity of an acetic acid solution if 34.57 mL of this solution are needed to neutralize 25.19 mL of 0.1025 M sodium hydroxide.

CH3COOH (aq) + NaOH (aq)Na+(aq) + CH3COOH-(aq) + H2O (l)

  1. For CeF3 the Ksp= 8 x 10-16.
  2. Calculate the molar solubility in water.
  1. Calculate the molar solubility in 0.2M CeCl3.
  1. Calculate the molar solubility in 0.2M NaF.

Answers:

  1. What is the pH of a 0.75M solution of ammonia? (Kb=1.8 x 10-5)

NH3 + H2O ßà NH4+ + OH- Kb=1.8 x 10-5= X2 pOH=-log(3.67 x 10-3M)

I 0.75M 0 0 0.75 pOH=2.44

C -X +X +X X= 3.67 x 10-3M= [OH-] pH=14 – 2.44= 11.56

E 0.75 – X X X

  1. What is the pH of a solution made by mixing 1.0L of 0.11M HCl with 3.0L of 0.080M NaF? (HF’s Ka=6.8 x 10-4)

HCl + NaFß à HF + NaCl **buffer solution= weak A and weak B

H+ + F- ßà HF weak base=0.13 mol F-

Mol HCl= 1.0L x 0.11mol/L= 0.11 mol HCL weak acid=0.11 mol HF

Mol NaF= 3.0L x 0.080mol/L= 0.24 mol NaF pH= pKa + log ([base]/[acid])

**Strong acid will completely neutralize weak base pH=3.17 + log (0.13/0.11)= 3.24

3.  Calculate the molarity of an acetic acid solution if 34.57 mL of this solution are needed to neutralize 25.19 mL of 0.1025 M sodium hydroxide.

CH3COOH (aq) + NaOH (aq)Na+(aq) + CH3COOH-(aq) + H2O (l)

M1V1=M2V2 X(34.57 mL)= (0.1025M)(25.19 mL) X= 0.747 M

  1. For CeF3 the Ksp= 8 x 10-16.
  2. Calculate the molar solubility in water.

CeF3 (s)à Ce+3 + 3F- Ksp=[ Ce+3][ F-]3

I ? 0 0 8 x 10-16= x(3x)3

C -x +x +3x x= 7.0 x 10-5 M

E ?-x x x

  1. Calculate the molar solubility in 0.2M CeCl3.

CeF3 (s)à Ce+3 + 3F- Ksp=[ Ce+3][ F-]3

I ? 0.2M 0 8 x 10-16= (0.2)(3x3)

C -x +x +3x x= 5.0 x 10-6 M

E ?-x 0.2+x x

  1. Calculate the molar solubility in 0.2M NaF.

CeF3 (s)à Ce+3 + 3F- Ksp=[ Ce+3][ F-]3

I ? 0 0.2M 8 x 10-16= (x)(0.2)3

C -x +x +3x x= 1.0 x 10-13 M

E ?-x x 0.2+x