Precipitation Reactions Flashcards

Chemical Reactions

Types of Reactions

• Synthesis: A + B \rightarrow AB
• Decomposition: AB \rightarrow A + B
• Single Replacement: A + BC \rightarrow AC + B
• Double Replacement: AB + CD \rightarrow AD + CB

Double Replacement Reactions

• Ions in two compounds exchange places in an aqueous solution to form new compounds.
• General form: AX + BY \rightarrow AY + BX
• Driving Forces: A double replacement reaction requires one of the following:
  • Formation of a precipitate.
  • Formation of a gas that bubbles out of solution.
  • Formation of water.
• No driving forces mean no reaction occurs.

Precipitation Reactions

• Reactions between two aqueous solutions of ionic compounds that produce an insoluble ionic compound (precipitate).

Predicting Products of Precipitation Reactions

1. Determine if the reaction is a double replacement reaction.
2. Identify the ions in each reactant.
3. Exchange ions: Combine the positive ion from one reactant with the negative ion from the other.
4. Write the formulas of the products, ensuring charges are balanced.
5. Determine the solubility of each product using solubility rules.
   • If a product is insoluble, it will precipitate (solid).
   • If both products are soluble, write "no reaction".
6. If a reaction occurs, write (aq) next to soluble products and (s) next to insoluble precipitates.
7. Balance the equation.

Solubility Rules

• Always Soluble:
  • Cations: Alkali metals (Group 1), Ammonium (NH_4^+
• Generally Soluble:
  • Halogen ions (Cl, Br, I) are soluble except with Hg^{2+}, Ag^+, and Pb^{2+} (HAPpy ions).
  • Sulfates (SO_4^{2-}) are soluble except with HAPpy ions and Ca^{2+}, Ba^{2+}, and Sr^{2+} (CBS ions).
• Generally Insoluble:
  • HAPpy ions (Hg, Ag, Pb) unless paired with always soluble anions.
  • Oxide and hydroxide ions except with alkali metals, ammonium, or CBS ions.
  • Carbonate, phosphate, sulfide, and sulfite except with alkali metals or ammonium.

Important Ions

• Sulfide
• Sulfite
• Sulfate
• Ammonium
• Phosphate
• Acetate