Equations for precipitation reactions
Equations representing precipitation reactions can be written in a variety of forms.
These are shown below using the reaction in which lead(II) chloride is precipitated on mixing aqueous solutions of lead(II) nitrate and sodium chloride.
A word equation uses names of reactants and products to describe the overall change.
A balanced overall equation represents reactants and products using formulae and has the same number and type of atoms in reactants as in products. Balancing is achieved by inserting coefficients as required in front of the formulae.
A balanced overall equation with states clarifies the physical form of each species.
These are shown below using the reaction in which lead(II) chloride is precipitated on mixing aqueous solutions of lead(II) nitrate and sodium chloride.
A word equation uses names of reactants and products to describe the overall change.
lead(II) nitrate + sodium chloride 
lead(II) chloride + sodium nitrate
lead(II) chloride + sodium nitrateA balanced overall equation represents reactants and products using formulae and has the same number and type of atoms in reactants as in products. Balancing is achieved by inserting coefficients as required in front of the formulae.
Pb(NO3)2 + 2NaCl PbCl2 + 2NaNO3
PbCl2 + 2NaNO3A balanced overall equation with states clarifies the physical form of each species.
Pb(NO3)2(aq)+ 2NaCl(aq) PbCl2(s) + 2NaNO3(aq)
A balanced ionic equation shows soluble species as hydrated ions. PbCl2(s) + 2NaNO3(aq)Pb2+(aq) + 2NO3–(aq) + 2Na+(aq) + 2Cl–(aq) PbCl2(s) + 2Na+(aq) + 2NO3–(aq)
A balanced net ionic equation focuses on the chemical change as species in the reaction mixture that are unchanged as a consequence of reaction (spectator ions) are not shown. PbCl2(s) + 2Na+(aq) + 2NO3–(aq) Pb2+(aq) + 2Cl–(aq) PbCl2(s)
PbCl2(s)