Chemistry

Problem

The balanced net-ionic equation for a precipitation reaction is

Pb^{2+}(aq) + 2\,I^{-}(aq) \to PbI_2(s)

. In a student’s particulate diagram, the reactant region contains two

Pb^{2+}

ions and four

I^{-}

ions, while the product region shows only one unit of solid

PbI_2

. Specify the simplest change required to make the diagram obey both mass and charge conservation.