AP Chemistry Exam Cram Session with Jeremy Kug

Introduction

• Intended for final study days/hours before the AP Chemistry exam.
• Offers a free PDF guided notes and a comprehensive review packet.
• Covers units 1 through 9 in AP Chemistry.

Unit 1: Fundamental Concepts and Mass Percent

• Mass Percent Concept:

  • Calculation involves atomic mass of elements.
  • Example: Magnesium Chloride (MgCl2)
    • Mg: 24.31, Cl: 35.45 (x2 for Cl2) → Total mass = 95.21 amu
    • Mg %: (24.31/95.21) x 100 ≈ 25.53%
    • Cl %: (70.90/95.21) x 100 ≈ 74.47%
  • Example: Calcium Chloride (CaCl2)
    • Ca: 40.08, Cl: 35.45 (x2) → Total mass = 110.98 amu
    • Ca %: (40.08/110.98) x 100 ≈ 36.11%
    • Cl %: (70.90/110.98) x 100 ≈ 63.89%
  • Patterns observed with different metal chlorides.

• Mass Spectrometry:

  • Used to determine isotopic composition and average atomic mass.
  • Example with a mass spectrum showing isotopes at 85 amu (75% abundance) and 87 amu (25% abundance).
  • Calculation of average atomic mass.

• Electron Configurations:

  • Write configurations starting from the beginning of the periodic table.
  • Examples: Chlorine (Cl), Chloride ion (Cl-), Aluminum (Al), Aluminum ion (Al3+), Fluorine (F), and others.
  • Understanding periodic trends like atomic radius.

Unit 2: Bonding and Molecular Geometry

• Lewis Structures:

  • Draw central atom, surrounding atoms, and electron pairs.
  • Examples: SF2, CO2.

• Sigma and Pi Bonds:

  • All single bonds are sigma bonds.
  • Double bonds: 1 sigma, 1 pi.
  • Triple bonds: 1 sigma, 2 pi.

• Hybridization and Molecular Geometry:

  • SP3, SP2 hybridizations.
  • Molecular geometries: Bent, Trigonal Planar, Tetrahedral, etc.
  • Bond angles: 104.5° for bent, 120° for trigonal planar, 109.5° for tetrahedral.

• Polarity and Intermolecular Forces:

  • Identifying polar molecules.
  • London dispersion forces, dipole-dipole forces, hydrogen bonding.

Unit 3: Intermolecular Forces and Properties

• Melting Points and Ion Sizes:

  • Comparison using Coulomb's law.

• Solubility:

  • Ion-dipole interactions in water.

Unit 4: Chemical Reactions and Stoichiometry

• Net Ionic Equations:

  • Identify and omit spectator ions.
  • Example reactions with magnesium, copper ions.

• Stoichiometry:

  • Convert to moles, use mole ratios, convert to final units.
  • Sample problems with silver ions and carbonate ions.

Unit 5: Kinetics

• Rate Laws:

  • Determine order of reaction with respect to reactants.
  • Sample problems with trial comparisons.
  • Rate constant calculation.

• Reaction Mechanisms:

  • Identify intermediates and rate-determining steps.

Unit 6: Thermodynamics

• Calorimetry:

  • Q = MCΔT calculations.
  • Heat transfer and thermal equilibrium.

• Enthalpy Calculations:

  • Using ΔH = Σ(products) - Σ(reactants).

Unit 7: Equilibrium

• Equilibrium Expressions:

  • Write expressions for KC and KP.

• Ice tables:

  • Solving equilibrium problems.

• Le Chatelier's Principle:

  • Predicting shifts in equilibrium.

Unit 8: Acids and Bases

• pH and pOH Calculations:

  • Relationships between hydronium, hydroxide concentrations.

• Strong and Weak Acids/Bases:

  • Identify and work with strong acids/bases.

• Salts and Acid-Base Properties:

  • Predicting nature of salts (acidic, basic, neutral).

• Titration Curves:

  • Determining concentration and Ka from titration curves.

Unit 9: Thermodynamics and Electrochemistry

• Entropy:

  • Understanding and predicting changes in entropy.

• Gibbs Free Energy:

  • Calculating ΔG to predict thermodynamic favorability.

• Galvanic Cells:

  • Understanding cell potentials and electron flow.
  • Writing overall balanced equations for galvanic cells.

Conclusion

• Encouragement for the AP exam.
• Reminder to share resources and study effectively.