Chemical Reactions

Ionic Theory of Solutions

  • Arrhenius proposed that certain substances generate freely moving ions in water, conducting electricity.

Electrolytes

  • Electrolyte: Dissolves in water, yielding an electrically conducting solution.

  • Strong Electrolyte: Mostly exists as ions in solution, e.g., soluble ionic compounds.

  • Weak Electrolyte: Partially ionizes in solution, e.g., most molecular substances.

Solubility Rules

  • Example Compound Analysis:

    • Hg2Cl2: Insoluble.

    • KI: Soluble.

Writing Chemical Equations

  • Complete ionic equations express strong electrolytes as separate ions.

Ion Equations

  • Complete Ionic Equation: Shows all ions in solution.

  • Net Ionic Equation: Excludes spectator ions.

Reaction Types

  • Precipitation Reactions: Form solid ionic substances from mixed solutions.

  • Acid-Base Reactions: Involve proton transfer.

  • Oxidation-Reduction Reactions: Involve electron transfer.

Predicting Precipitation Reactions

  1. Predict products by exchanging parts.

  2. Determine state of products (s, l, g, aq).

  3. No net reaction if all products are aqueous.

Acid-Base Definitions

  • Acid: Produces hydrogen ions in water.

  • Base: Produces hydroxide ions in water.

  • Brønsted-Lowry Definition:

    • Acids donate protons.

    • Bases accept protons.

Neutralization Reactions

  • Reaction between acid and base forming an ionic compound (salt) and water.

Strong and Weak Acids/Bases

  • Strong Acids: Completely ionize (e.g., HCl).

  • Weak Acids: Partly ionize (e.g., HCN).

  • Strong Bases: Exist as ions in solution (e.g., NaOH).

  • Weak Bases: Partly ionize in solution (e.g., Ammonia).

Oxidation-Reduction Reactions

  • Electrons are transferred, changing oxidation states.

  • Oxidizing Agent: Gains electrons (is reduced).

  • Reducing Agent: Loses electrons (is oxidized).

Common Reaction Types

  • Combination Reaction: Two or more substances form one substance.

  • Decomposition Reaction: One compound produces two or more substances.

  • Displacement Reaction: An element displaces another in a compound.

  • Combustion Reaction: Substance reacts with oxygen, releasing heat.

Balancing Redox Reactions

  • Use half-reaction method to balance oxidation and reduction processes, ensuring electron conservation.