General Chemistry Review Lecture Notes

Overview of Topics

• First Semester Chemistry Topics
  • Stoichiometry
  • Percent Yield
  • Empirical Formulas
  • Limiting Reactants
  • Conversions (grams to moles to atoms/molecules)
  • Dilution Problems
  • Balancing Equations
  • Oxidation Numbers
  • Gas Laws (PV = nRT)
  • Vapor Pressure and Partial Pressure
  • Graham's Law of Diffusion
  • Kinetic Molecular Theory
  • Solutions and Concentrations (Molarity and Molality)
  • Mass Relationships in Reactions
  • Thermochemistry (enthalpy calculations, Hess's Law)
  • Intermolecular Forces
  • Colligative Properties (boiling point elevation, freezing point depression, osmotic pressure)

1. Ions and Atomic Structure

• Understanding Ions
  • An ion has an unequal number of protons and electrons.
  • Example: For an ion with a charge of +3, there are 3 more protons than electrons.
  • Atomic Number: Number of protons (e.g., Al with atomic number 13 has 13 protons).
  • Mass Number: Number of protons + neutrons.
  • Neutrons Calculation: Mass number - Atomic number
  • Electrons Calculation: Atomic number - Charge.

2. Naming Compounds

• Molecular vs. Ionic Compounds
  • Molecular compounds: use prefixes (mono-, di-, tri-, etc.).
  • Ionic compounds: no prefixes, e.g., AlCl3 = Aluminum Chloride.

3. Percent Composition

• Formula: % Composition = (mass of element / total mass) x 100%.
  • Example calculation for Aluminum in Aluminum Sulfite.

4. Stoichiometry in Reactions

• Balanced Chemical Equations: Essential for stoichiometric conversions.
  • Example: N2 + H2 → NH3 balanced as H2 + 3/2 H2 → 2 NH3.
  • Limiting Reactants: Identify the limiting reagent to calculate the maximum product yields.

5. Molarity and Concentrations

• Calculating Molarity: Molarity (M) = moles of solute / liters of solution.
• Dilution Problems: M1V1 = M2V2 (concentration and volume before and after dilution).

6. Gas Laws

• Ideal Gas Law: PV = nRT (where R is the gas constant).
• Combined Gas Law: P1V1/T1 = P2V2/T2.

7. Kinetic Molecular Theory

• Explains the behavior of gases in terms of molecular motion.

8. Thermodynamics

• Enthalpy Changes: Calculate enthalpy using bond association energies and formation enthalpies.
• Calorimetry: Q = mcΔT.

9. Intermolecular Forces

• Types: Hydrogen bonds > Dipole-Dipole > London Dispersion Forces.

10. pH Calculations

• pH and pOH Relation: pH + pOH = 14.
• Calculate pH from the concentration of hydroxide or hydronium ions.

11. Colligative Properties

• Boiling Point Elevation: ΔT = iKbm (where i = van't Hoff factor).
• Freezing Point Depression: Similar to boiling point elevation.

12. Average Atomic Mass Calculation

• Use relative abundances of isotopes to find weighted average.

13. Percent Yield Calculation

• Actual yield vs. theoretical yield: Percent Yield = (actual yield / theoretical yield) x 100.

Conclusion

• Review different concepts regularly and practice problem-solving to reinforce understanding of chemistry principles.