Chemical Reactions & Equations

Chemical Terminology

• Chemical Formula: Represents elements and the number of atoms present in a compound.
• Chemical Equation: Symbolic representation showing the relationship between reactants and products.
• Reactants: Elements or compounds entering a reaction.
• Products: Elements or compounds resulting from a chemical reaction.

Chemical Components

• Coefficients: Numbers placed before chemical formulas to indicate quantity.
• Subscripts: Numbers below chemical symbols indicating the number of atoms in a compound.
• Molecular Formula: Indicates types and amounts of atoms in a molecule, without specifying arrangement.

Reaction Types

• Balanced Equation: An equation where the number of atoms for each element is the same on both sides.
• Precipitate: A solid formed from a solution in a chemical reaction.

Laws of Chemistry

• Law of Conservation of Mass: Total mass remains constant in physical and chemical changes, indicating matter is neither created nor destroyed.
• Element: A pure substance consisting of one type of atom.

Types of Reactions

• Synthesis: Combines simple reactants into more complex products (A+B → AB).
• Decomposition: A single compound breaks down into simpler products (AB → A + B).
• Single Replacement: An element replaces another in a compound (AB + C → A + BC).
• Double Replacement: Two compounds exchange partners (AB + CD → AC + BD).
• Combustion: Rapid reaction with oxygen, typically producing heat and light.

Reaction Classification Examples

• Synthesis Example: 2Mg + 1O₂ → MgO.
• Decomposition Example: 2H₂O₂ → 2H₂O + 1O₂.
• Single Replacement Example: 1Mg + 2HCl → 1MgCl₂ + 1H₂.
• Double Replacement Example: NaOH + HCl → NaCl + H₂O.

Balancing Chemical Equations

• Balancing involves adjusting coefficients to maintain equal atoms of each element on both sides.
• Example of balancing: The equation CaO + H₂O → Ca(OH)₂ is balanced.

Concept Applications

• Using relatable scenarios for reaction types:
  • Synthesis: A new couple forms at a prom.
  • Decomposition: A couple breaks up at a prom.
  • Single Replacement: A couple switches partners with a single student.
  • Double Replacement: Two couples switch partners, forming new couples.