1. Matter & Bonding Lesson # 8
Double Displacement

2. Double Displacement
A double displacement reaction involves elements in different compounds displacing each other or exchanging places.
General Formula: AB + CD → AD + BC
A clue that the reaction is double displacement is that two ionic compounds are involved.

3. D.D. (continued)
Visuals: the two reactants are always aqueous, while one of the products will be a solid precipitate.
Real-Life Example: neutralizing acids and bases to create water.
Example: Pb(NO3)2 + 2 KI → PbI2 + 2 KNO3
Example: CaCO3 + 2 HCl → H2CO3 + CaCl2
Example: H2SO4 + 2 NaOH → 2 H2O + Na2SO4

4. Solubility
Solubility is a measure of the extent to which a solute dissolves in a solvent at a given temperature and pressure.
Something like chalk, calcium carbonate, has a low solubility, and something like table salt, sodium chloride, has a high solubility.
In a double displacement reaction, two aqueous ionic compounds react to form a new solid or water compound and a new aqueous ionic compound. This new solid is called a precipitate.
If a precipitate or water does not form after two ionic compounds are mixed, then no reaction occurs between them.
You need to use your table of solubility rules to determine which products, if any, will become precipitates once the reaction occurs. First you need to determine potential products based on the reactants.

5. Practice a) sodium chloride + silver nitrate →
b) hydrochloric acid + magnesium hydroxide →
c) sodium chloride + potassium bromide →