Predicting Products of Ionic Double Replacement Reactions

Key Concepts

• Ionic Double Replacement Reaction: Two ionic compounds exchange ions.
  • Ionic Compound: Consists of a cation (positive) and an anion (negative).
• Objective: Predict products, determine solubility, and balance the equation.

Steps to Predict Products

1. Write the Ions for Reactants: Identify the ions present in the reactants.
2. Recombine Ions: Switch partners between cations and anions.
3. Determine Solubility: Check if a precipitate forms by consulting solubility rules.
4. Balance the Equation: Ensure the number of atoms for each element is the same on both sides.

Solubility Rules Overview

• Soluble Compounds:
  • Group 1 cations (e.g., sodium, lithium, potassium).
  • Chloride, bromide, iodide (except with silver, mercury, lead).
  • Acetate, bicarbonate, nitrate, chlorate.
  • Sulfates (except with group 2 metals, lead 2, iron 3).
• Insoluble Compounds:
  • Carbonates, chromates, phosphates, sulfides (except with group 1 cations and ammonium).
  • Hydroxides (except with group 1 cations and barium).

Example: Sodium Carbonate with Iron 3 Sulfate

Reactants Identification

• Sodium Carbonate: Na⁺, CO₃²⁻
• Iron 3 Sulfate: Fe³⁺, SO₄²⁻

Formulas

• Sodium Carbonate: Na₂CO₃ (Aqueous because sodium compounds are soluble)
• Iron 3 Sulfate: Fe₂(SO₄)₃ (Aqueous based on sulfate solubility rules)

Predicting Products

• Partner Switch:
  • Sodium sulfate: Na₂SO₄ (Soluble, sodium is a Group 1 cation)
  • Iron 3 carbonate: Fe₂(CO₃)₃ (Insoluble, forms a solid as per carbonate rules)

Reaction Occurrence

• Reaction occurs if a solid forms. Here, iron 3 carbonate is the precipitate.

Balancing the Equation

• Initial Products: Na₂SO₄ (Aq) + Fe₂(CO₃)₃ (Solid)
• Balanced Equation:
  • Adjust coefficients to ensure same number of each atom on both sides.
  • Example balancing might involve ensuring equal numbers of sodium ions, sulfate ions, etc.

Practice Suggestions

• Work on predicting reactions and balancing equations.
• Understand and memorize solubility rules for effective prediction.