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Types of Reactions

Synthesis (or Combination) Reaction

  • Two or more reactants (simple) to one product (complex)
  • General Equation: A + X --> AX
  • eg: 3H₂(g) + N₂(g) --> 2NH₃

Decomposition Reaction

  • One reactant (complex) to two or more products (simple)
  • General Equation: AX --> A + X
  • eg: PbCO₃(s) --> PbO(s) + CO₂(g)

Single-Replacement (Exchange) Reaction

  • One element replaces another of the same type charge
  • General Equation: A⁺ + B⁺X⁻ --> AX + B 
  • eg: Cl₂(g) + KBr(aq) --> KCl(aq) + Br₂(g)

Double Replacement (Exchange) Reaction

  • Exchange cations and anions
  • An acid and base react to form water
  • General Equation: A⁺X⁻ + B⁺Y⁻ --> AY + BX
  • eg: 2AgNO₃(aq) + MgCl₂(aq) --> 2AgCl(s) + Mg(NO₃)₂(aq)

Combustion Reaction

  • Substances combine with O₂-- must release heat or light
  • Balance in order of C, H, then O
  • General Equation: X + O₂--> CO₂ + H₂O
  • eg: 2C₅H₁₀(g) +15O₂(g) → 10CO₂(g) + 10 H₂O(l)

Moles

The Mole is the SI unit for amount of substance. It is used as a counting unit used to count a large number of atoms.

1 mol of atoms = Avogadro's number

  • = 602 sextillion; 602,000,000,000,000,000,000,000
  • 6.02x10²³

Molar Mass:

  • The mass of 1 mol of a substance is called the molar mass
  • Written in terms of grams per mole (g/mol)
  • eg: Mercury (Hg) - 200.6 g/mol

Avogadro's number:

  • Is the number of particles in exactly one mole of a pure substance
  • Can be written as:
    • 6.022x10²³ particles/mol
    • 6.022x10²³ atoms/mol
    • 6.022x10²³ molecules/mol

Mole Conversions:

 

  • Use the factor label method:
  • Start with the end in mind
  • List your given (put your given over 1)
  • Use the appropriate conversion factor
  • Check your units

mass to moles: (# of grams/1)( 1 mol/Molar Mass (g))

moles to mass: (# of moles/1)(Molar Mass (g)/1 mole)