The balanced equation for the decomposition of lead(II) nitrate by heat is:

2 Pb(NO₃)₂ (s) → 2 PbO (s) + 4 NO₂ (g) + O₂ (g)

Here's what happens:

* Lead(II) nitrate (Pb(NO₃)₂) decomposes when heated.

* Lead(II) oxide (PbO), a yellow solid, is formed.

* Nitrogen dioxide (NO₂) gas is released, which has a reddish-brown color.

* Oxygen gas (O₂) is also released.

This reaction is an example of a thermal decomposition reaction, where heat provides the energy needed to break down the reactant.