EQUATIONS FOR THE REACTIONS OF IONS
9.1: REACTIONS OF IONS IN SOLUTION
!  Recall,
from Unit 2:
!
BaCl2(aq) + Na2SO4(aq)
!
But, sodium chloride (aq) does not actually exist as
NaCl in water – it dissociates into its ions: Na+
BaSO4 (s) + 2 NaCl (aq)
and Cl-
TOTAL IONIC EQUATIONS
!  A
chemical equation where all soluble ionic
compounds are written as dissociated ions. (anything
aqueous dissociates)
!  Must still be balanced (check the charges AND the
coefficients!)
!  ie:
Ba2+(aq) + 2 Cl-(aq) + 2 Na+(aq) + SO42-(aq) " BaSO4(s) + 2 Na+(aq) + 2 Cl-(aq)
NET IONIC EQUATIONS
!  The
sodium and chlorine ions appear on both sides of the
equation as ions: they remain unchanged in the reaction!
!  These are called spectator ions.
!  They can be omitted from the equation to make it
simpler.
!  The net ionic equation includes only the entities that
react during a reaction!
!  ie:
Ba2+(aq) + 2 Cl-(aq) + 2 Na+(aq) + SO42-(aq) " BaSO4(s) + 2 Na+(aq) + 2 Cl-(aq)
Ba2+(aq) + SO42-(aq) " BaSO4(s)
STEPS FOR WRITING TOTAL AND NET IONIC
EQUATIONS
1. Write the balanced chemical equation with
states for the reaction (just like Unit 2).
2. Write the total ionic equation by showing all of
the soluble compounds as ions.
3. Cancel spectator ions.
4. Write the net ionic equation.
**Note: can be done for both single and double
displacement reactions
!  Example
1: Write the total ionic equation and the net
ionic equation for the reaction of solutions of lead (II)
nitrate and potassium iodide.
!  Example
2: Write the net ionic equation for the
reaction:
aluminum metal is placed in a solution of
copper (II) chloride.