Skip to main content

Decomposition Reactions

Mahi Tuatahi

  1. Give the general equation for:
    • A precipitation reaction
    • A displacement reaction
    • A combination reaction
  2. Give an observation that you might make to indicate that each type of reaction has occurred.

Ngā Whāinga Ako

Decomposition Reactions

\begin{aligned} AB \xrightarrow{heat} A + B \end{aligned}


Mercury (II) oxide is heated in a test tube. The solid is seen to change colour and a gas is given off.

  1. If the gas is oxygen, how could you confirm this?
  2. Write a word equation.
  3. Write a symbol equation (with states) and balance it.

  1. A glowing splint in the presence of oxygen gas, will reignite.
  2. mercury oxide $\xrightarrow{\text{heat}}$ mercury + oxygen gas
  3. $2HgO_{s} \xrightarrow{\text{heat}} 2Hg_{l} + O_{2g}$