AP Chemistry Exam Review Packet

Possible Topics from Chem I Material: Gas Laws, PT Trends, and Bond Energy

1.)State the 5 postulates of the kinetics molecular theory of gases.

2. ) Write the correct electron configuration for nickel.

3.)Which atom below has the smallest atomic radius?

  1. Na
  2. Mg
  3. Rb
  4. Ba
  5. Li

4.)If a 250mL sample of H2 gas is collected at 32ºC and 345torr, what is the temperature of the sample if it then expands to 350mL?

  1. 25ºC
  2. 45ºC
  3. 100ºC
  4. 154ºC
  5. 213ºC

5.)Which of the following atoms has the lowest electronegativity?

  1. Y
  2. Ra
  3. Fr
  4. F
  5. Cl

6.)Which of the following types of bonds has the lowest bond energy?

  1. Hydrogen bond
  2. Polar covalent bond
  3. Nonpolar covalent bond
  4. London dispersion forces
  5. All of these types of bonds have equal bond energy

Lewis Structures, Bonding, and Geometries

1.)What is the frequency of a photon of blue light that has a wavelength of 500nm?

  1. 6x1014s-1
  2. 1.5x1011s-1
  3. 3x108s-1
  4. 1.5x102s-1
  5. 1.67x10-15s-1

2.)What is the shape of an s orbital?

  1. Spherical
  2. 2 lobes
  3. 4 lobes
  4. 8 lobes
  5. Dumbbell

3.)In a krypton atom, which atomic orbitals contain the valence electrons?

  1. 3d
  2. 4p
  3. 3s and 3p
  4. 4s and 4p
  5. 4s, 3d, and 4p

4.)What are the formal charges on C, O, and Cl, respectively, in the COCl2 molecule?

  1. 0,0,0
  2. 0,-1,+1
  3. 0,+1,-1
  4. +1,-1,0
  5. -1,0,+1

5.)What is the hybridization of the central As atom is AsF5?

  1. sp
  2. sp2
  3. sp3
  4. sp3d
  5. sp3d2

6.)The valence electron of potassium can have which of the following sets of 4 quantum numbers (n, l, ml, ms)?

  1. (4, 1, 0, ½)
  2. (4, 0, 1, ½)
  3. (3, 1, 1, ½)
  4. (4, 0, 0, ½)
  5. (5, 0, 0, - ½)

7.)Consider the nitrite ion, NO2-.

  1. Draw the Lewis structure for the nitrite ion including all resonance structures.
  2. Describe the hybridization of the nitrogen atom in the nitrite ion.
  3. Calculate the formal charge on all atoms in the first structure that you drew.
  4. How many sigma bond and pi bonds are present in this ion?
  5. What is the electron-pair geometry for this ion? What is the molecular geometry for this ion?

Solutions

1.)You need to prepare a 0.34M solution of KOH for an experiment. What mass of solid KOH do you need in order to prepare 75mL of this solution?

  1. 0.0255g and add it to 75mL of water
  2. 1.43g and add it to 75mL of water
  3. 1.43g and add enough water to make 75mL of solution
  4. 2.55g and add enough water to make 75mL of solution
  5. 25.5g and add it to 75mL of water

2.)Which of the following solutions will have the lowest freezing point?

  1. 0.1m CaI2
  2. 0.1m NaI
  3. 0.1m C6H12O6
  4. 0.1m Mg3(PO4)2
  5. 0.1m K3PO4

3.)You have been asked to prepare 50mL of a 0.75M solution of NaCl. All you have is a 2.5M solution of NaCl. How would you prepare the necessary solution?

  1. Add 15mL of the 0.75M solution to 50mL of water
  2. Add 15mL of the 0.75M solution to 35mL of water
  3. Add 15mL of the 2.5M solution to 50mL of water
  4. Add 15mL of the 2.5M solution to 35mL of water
  5. You cannot determine this from the information given.

4.)A 250g sample of an unknown substance is dissolved in 1kg of pure water. The freezing point of the solution was found to be -7.18ºC. You should know the freezing point of pure water. The Kf of water is 1.86ºCkg/mol, and the Kb of water is 0.512ºCkg/mol. Assume that the solute is a nonelectrolyte.

  1. What is the molality of the solution?
  2. What is the molar mass of the unknown substance?
  3. Knowing the boiling point of pure water, what is the boiling point of the solution?
  4. Was the use of the van’t Hoff factor necessary in this problem? Why or why not?

Basic Equilibrium

1.)At 773K, the Kc for the reaction below is 0.013. What is the Kp for this reaction?

H2(g) + ½ O2(g) H2O(g)

  1. 1.10
  2. 0.016
  3. 0.103
  4. 0.908
  5. 1.62x10-3

2.)Write the equilibrium constant expression for the following reaction.

MgCO3(s) + 2HCl(g) MgCl2(s) + CO2(g) + H2O(l)

3.)For an exothermic reaction at equilibrium, a decrease in temperature will cause the reaction to

  1. shift to the left
  2. shift to the right
  3. go faster
  4. go slower
  5. not change

4.)Consider the following equilibrium reaction:

2SO3(g) 2SO2(g) + O2(g)ΔH = +197kJKc = 5.6x10-5

  1. Write an equilibrium constant expression for Kc for this reaction.
  2. What are the equilibrium concentrations for all species in the equation if you initially have only 0.55mol of SO3 in a 2L flask?
  3. What is Kp for this reaction at 300K?
  4. Predict the shift of equilibrium if each of the following changes occurs and justify your answer.
  5. Additional oxygen gas is added
  6. Sulfur dioxide is removed from the flask
  7. The pressure is increased by adding helium gas
  8. The temperature is increased
  9. The volume of the flask is increased
  10. What is the equilibrium constant value, Kc, for the following reaction?

SO2 + ½ O2 SO3

5.)Consider the following reaction:

H2 + I2 2HI

0.025mol of both I2 and Br2 are added to a 1L flask at 773K. The reaction is allowed to come to equilibrium. The equilibrium constant, Kc, is measured as 45.

a. Write the equilibrium constant expression for this reaction.

b. Calculate the equilibrium concentrations for all species in the reaction.

c. What is the Kp of this reaction at the same temperature?

d. How would adding 0.45mol of HI affect the reaction? Explain your answer.

Acid Base Equilibrium

1.)A titration of 25mL of 0.25M formic acid (Ka=1.7x10-4) with 0.15M NaOH reached its equilivalence point. If the [H+]=0.214M at this point, which indicator is most suitable for this reaction?

  1. Crystal Violet (pKa=1)
  2. Thymol Blue (pKa=2)
  3. Methyl Orange (pKa=3.75)
  4. Bromocresol Purple (pKa=6)
  5. Alizarin Yellow (pKa=11)

2.)The pKa for hypochloric acid (HClO) is 7.52. What is the pKb for the conjugate base of this acid?

  1. 2.13
  2. 6.48
  3. 7.12
  4. 8.89
  5. 10.11

3.)Tell what occurs at the equilvalence point of a reaction.

4.)150mL of 0.5M propanoic acid, HC3H5O2 (Ka=1.3x10-5) is titrated with 0.25M KOH.

  1. How much KOH must be added to reach the equivalence point of this titration?
  2. What is the pH halfway to the equivalence point?
  3. What is the pH at the equivalence point?
  4. What is the pH at 20mL over the equivalence point?
  5. Draw a rough sketch of the titration curve for this titration.

5.)A 200mL sample of 0.1M NH4Cl solution is added to 160mL of a 0.2M NH3 solution. The value of Kb for ammonia is 1.8x10-5.

  1. What is the pH of the buffer system?
  2. What would the new pH of the system be if 0.2g of NaOH were added to the system?
  3. What would the new pH of the system be if 20mL of 0.01M HCl were added to the system?

Solubility Equilibrium

1.)The Ksp of BaSO4 in water is 1.1x10-10. What is the molar solubility of BaSO4 in water?

  1. 4.79x10-4M
  2. 4.79x10-5M
  3. 1.1x10-10M
  4. 1.05x10-5M
  5. 1.05x10-4M

2.)Assuming that temperature remains constant at 298K, the Ksp for CaF2 is

4.0x10-11 and the Ksp for CaC2O4 is 2.3x10-9.

  1. Write the balanced equation for the solubility equilibrium reaction for each of the 2 salts. Also, write the Ksp expression for each.
  2. What is the molar solubility of CaF2 in water?
  3. What is the molar solubility of CaC2O4 in water?
  4. If 50.0mL of 0.0025M is added to 50.0mL of 1.0x10-5M Na2C2O4, will any CaC2O4 precipitate?
  5. If an aqueous solution of Ca(NO3)2 is added to 1.0L of a solution containing 0.50mol of F- and 0.25mol of C2O42-, which salt will precipitate first, assuming that the solution volume remains 1.0L?

Thermodynamics

1.)For the following reaction, choose the following signs for the 3 thermodynamic state functions given below.

SO2(g) S(s) + O2(g)exothermic

  1. ΔH+, ΔS+, ΔG+
  2. ΔH-, ΔS-, ΔG-
  3. ΔH+, ΔS-, ΔG-
  4. ΔH-, ΔS+, ΔG-
  5. ΔH-, ΔS+, ΔG+

2.)Solid sulfur is burned in air producing sulfur dioxide gas.

S(s) + O2(g) SO2(g)ΔH = -296kJ

What is the enthalpy change if 1.0kg of solid sulfur is burned?

  1. +9230kJ
  2. -9.23kJ
  3. -9.49kJ
  4. -296kJ
  5. -9230kJ

3.)State the 1st Law of Thermodynamics, the 2nd Law of Thermodynamics, and the 3rd Law of Thermodynamics.

4.)Which of the following describes the equilibrium constant for a spontaneous reaction?

  1. K=0
  2. K<0
  3. K=1
  4. K<1
  5. K>1

5.)2SO2(g) + O2(g) 2SO3(g)

Substance / ΔH (kJ/mol) / S (J/molK)
SO2(g) / -297 / 249
SO3(g) / -396 / 257
O2(g) / 0 / 205

If the reaction above is carried out at 298K and 1atm pressure, complete the following:

  1. What is the change in enthalpy of this reaction?
  2. What is the change in entropy of this reaction?
  3. What is ΔG for this reaction at this temperature?
  4. Is the reaction endothermic or exothermic? Justify your answer.
  5. Explain why ΔS is positive or negative at this temperature.
  6. Is the reaction spontaneous at 298K? Justify your answer.
  7. What is the value of K at this temperature?

Kinetics

1.)The kinetics of the following reaction was investigated. When the initial concentration of A is doubled and the concentration of B is held constant, the rate doubles. When the initial concentration of B is doubled, and A is held constant, the rate quadruples. What is the rate law for the reaction?

  1. Rate=k[A][B]
  2. Rate=k[A]2[B]3
  3. Rate=k[A][B]2
  4. Rate=k[A]3[B]
  5. Rate=k[A]2[B]

2.)A plot of 1/[NO2] versus time for the decomposition of NO2 was found to be linear. This means that

  1. The reaction is zero order
  2. The reaction is 1st order
  3. The reaction is 2nd order
  4. The reaction is 3rd order
  5. Order cannot be determined from the information given

3.)In the following mechanism, which species acts as a catalyst?

A + B  C

A  C + D

A + D  B + E

a. A

b. B

c. C

d. D

e. E

4.)Consider the following:

NO + Br2(k1)—(k-1) NOBr2FAST

NOBr2 + NO –(k2) 2NOBrSLOW

a. Write the balanced overall reaction.

b. Identify the rate determining step.

c. Write the rate law that is most consistent with this mechanism.

d. Based on your rate law, what affect would the concentration of NO (while keeping all other concentrations constant) have on the rate?

5.)Consider the following reaction:

2NO(g) + O2(g) 2NO2(g)

Experiment / [NO] / [O2] / Rate (mol/Ls)
1 / 0.0126 / 0.0125 / 7.05x10-3
2 / 0.0252 / 0.0250 / 5.64x10-2
3 / 0.0252 / 0.0125 / 2.82x10-2
  1. Determine the rate law for this reaction.
  2. Calculate the rate constant, k, for this reaction, including the correct units.
  3. Calculate the rate of the reaction when [NO] is 1.5M and [O2] is 0.75M.