Types of Reactions (Review)

Synthesis and Decomposition Reactions

    Synthesis Reactions:

  • Involve a single compound splitting into multiple smaller compounds and/or elements
  • Usually in the form: A → B + C, however there can be more than two products in some cases
  • Examples:
    • CaF2 → Ca + F2
    • 2H2O2 → 2H2O + O2

    Decomposition Reactions:

  • Involve multiple compounds and/or elements combining into a single larger compound
  • Usually in the form: A + B → C, however there can be more than two reactants in some cases
  • Examples:
    • 2Mg + O2 → 2MgO
    • N2 + 3H2 → 2NH3

    Tips for Synthesis and Decomposition Reactions:

  • Ionic compounds will generally decompose into their metal and non-metal components
    • If the non-metal is a diatomic element, remember to put the 2 subscript (e.g. Cl2)
  • Metal and non-mental components will generally synthesize an ionic compound, which can be determined using valence charges
    • When dealing with multivalent metals, use the most common valence charge
  • When dealing with covalent compounds, usually common/familiar substances will end up as synthesis/decomposition products (e.g. H2O, CO2)

Single and Double Displacement Reactions

    Single Displacement Reactions:

  • Involve a single element replacing another element which is in a compound
  • General form: A + BC → AC + B
  • Examples:
    • Cl2 + CaBr2 → CaCl2 + Br2
    • Li + H2O → LiOH + H2

    Reactivity Series:

  • Some elements are more reactive than others, which can be shown using a reactivity series (list of elements ordered by reactivity)
  • Using an activity series, you can determine whether an element will replace another in a compound based on their relative reactivities, where more reactive elements will replace less reactive elements
  • Example: knowing that chlorine is more reactive than iodine, we can say that I2 + NaCl will result in no reaction (N.R.), however switching them will give a reaction: Cl2 + NaI → I2 + NaCl

    Double Displacement Reactions:

  • Involve two ionic compounds with two ions each, where the compounds exchange/trade ions
  • General form: AB + CD → AD + CB
  • Examples:
    • BaCl2 + Na2SO4 → Ba2SO4 + 2NaCl
    • HCl + NaOH → H2O + NaCl

Combustion and Neutralization Reactions

    Combustion Reactions:

  • Involve a substance (often a hydrocarbon) reacting with oxygen to produce heat and other products
  • General form (hydrocarbons): CnHm + O2 → CO2 + H2O
  • Examples:
    • CH4 + 2O2 → CO2 + 2H2O
    • C3H8 + 5O2 → 3CO2 + 4H2O

    Neutralization Reactions:

  • A type of double displacement reaction involving an acid and a base reacting to form water and a salt
  • General form: Acid + Base → H2O + Salt
  • Examples:
    • HCl + NaOH → H2O + NaCl
    • H2SO4 + 2KOH → K2SO4 + 2H2O