1. IONIC EQUATIONS

2. Solution of an Ionic Compound

3. Solution of an Ionic Compound (cont.)

4. Precipitation Reactions
A precipitation reaction is a specific type of double replacement reaction.
In a precipitation reaction, one product is insoluble in water.
As that product forms, it emerges, or precipitates, from the solution as a solid.
The solid is called a precipitate.
For example,
Ca(NO3)2 (aq) + Na2CO3 (aq)
® CaCO3 (s) + 2NaNO3 (aq)

5. When the Ca(NO3)2 dissolves, the Ca2+ and NO3- ions are separated and surrounded by water molecules.
Solution of Ca(NO3)2

6. Solution of Ca(NO3)2 and Na2CO3 at the time of mixing, before the reaction

7. Product Mixture for the reaction of Ca(NO3)2 and Na2CO3

8. Complete Ionic Equations
Equations that show each substance exactly how it exists.
Aqueous ionic compounds are shown as separate ions.
Solids, liquids, and gases are written exactly the same as before.

9. Complete Ionic Equation

10. Spectator Ions
Ions that don’t change during the reaction are called spectator ions.
Spectator ions can be recognized because they are separate and surrounded by water molecules both before and after the reaction.
Spectator ions are important for delivering other ions into solution but they are not actively involved in the reaction.

11. Ca2+(aq) + CO32-(aq) ® CaCO3 (s)
Net Ionic Equations
An equation written without spectator ions is called a net ionic equation.
Ca2+(aq) + CO32-(aq) ® CaCO3 (s)
The net ionic equation only shows the things that are actually changing in the chemical reaction.
It is a more accurate representation of what is actually happening.

12. EXAMPLE
K2SO4 (aq) + CaCl2 (aq) KCl (aq) + CaSO4 (s)

13. What about single replacement?
Follow the same rules as with the double replacement.
1. Write balanced chemical equations identifying the state of matter.
2. Write complete ionic equations (CIE) showing aqueous ionic compounds as separate ions.
3. Write net ionic equations (NIE) showing only the species that are changed.

14. EXAMPLE
Cl2 (g) NaI (aq)  I2 (s) NaCl (aq)