Exam 2 Study Guide: Principles of Chemistry I (1211K)

Chapter 2: Nomenclature

  • Chemical Nomenclature: The systematic naming of chemical compounds.

    • Importance of correct naming for communication in science.

    • Different rules for ionic, covalent, and acid naming.

Writing and Balancing Chemical Equations

  • Chemical Equation: A representation of a chemical reaction using symbols and formulas.

  • Balancing Chemical Equations: Ensures that the number of atoms for each element is the same on both sides of the equation.

    • Steps to Balance:

    • Write the unbalanced equation.

    • Count the atoms of each element in the reactants and products.

    • Adjust coefficients to balance each type of atom.

    • Check to ensure that all atoms are balanced.

Chapter 3: Calculations

  • Calculating Molecular/Formula Mass: The sum of the atomic masses of all the atoms in a molecule or empirical formula.

    • Molecular Mass Example:

    • Water (H₂O):

      • H: 1.01 g/mol × 2 = 2.02 g/mol

      • O: 16.00 g/mol

      • Total = 18.02 g/mol

  • Gram to Mole Conversions: Conversion between grams of substance and moles using molar mass.

    • Formula:

    • Moles = Mass (g) / Molar Mass (g/mol)

  • Calculating Percent Composition: The percentage by mass of each element in a compound.

    • Formula:

    • Percent Composition = (Mass of Element / Molar Mass of Compound) × 100%

  • Determining Percentages of C, H, and O from Combustion Data:

    • Combustion analysis for hydrocarbons provides mass of CO₂ and H₂O produced, which can be used to calculate percentages based on molar ratios.

  • Molecular Formula: A formula that shows the actual number of each atom in a molecule.

    • Relationship to empirical formula: Molecular Formula = (Empirical Formula)n, where n is a whole number.

  • Limiting Reactants: The reactant that is completely consumed in a reaction, limiting the amount of product formed.

    • Calculation:

    • Determine the moles of each reactant involved.

    • Calculate the theoretical yield based on the limiting reactant.

  • Calculating Percent Yield: A measure of the efficiency of a reaction's conversion of reactants to products.

    • Formula:

    • Percent Yield = (Actual Yield / Theoretical Yield) × 100%

Chapter 4: Electrolytes vs. Non-Electrolytes

  • Electrolytes: Substances that dissociate into ions when dissolved in water, conducting electricity.

    • Examples: Sodium chloride (NaCl), potassium nitrate (KNO₃).

  • Non-Electrolytes: Substances that do not dissociate into ions in solution, and therefore do not conduct electricity.

    • Examples: Sugar (C₁₂H₂₂O₁₁), ethanol (C₂H₅OH).