2. Double Replacement Reactions

3. Exchange of ions between two compounds
Typically a precipitate is produced
AX+BY -> AY+BX
EX. Al2(CO3)3 + K2O -> Al2O3 + K2CO3

4. Anions switch place with anions and cations switch place with cations.
Ex. NaCl + AgNO3 ->
NaNO3 + AgCl

5. Al2(SO4)3 + HNO3
Al(NO3)3 + H2SO4 --->
Ca(OH)2 + HCl ->
CaCl2 + H2O

6. Do all reactions always occur?
No!
Must have one soluble and one insoluble compounds.
Soluble – dissolves in water, its state is aqueous
Insoluble - forms a precipitate, a solid compound

8. Rules
One of the products is only slightly soluble and precipitates from solution
One of the products is a gas
One product is a molecular compound such as water

9. Silver nitrate(aq) + potassium chromate (aq) ->
Sodium sulfate(aq) + barium chloride(aq) ->
Silver chromate(s) + potassium nitrate(aq)
AgNO3(aq) + K2CrO4(aq)-> Ag2CrO4(s)+KNO3(aq)
Barium sulfate(s) + sodium chloride(aq)
Na2SO4(aq) + BaCl2(aq) -> BaSO4(s) + NaCl(aq)

10. Calcium hydroxide(aq)+hydrochloric acid(aq)->
Potassium chloride(aq)+sulfuric acid(aq)->
Calcium chloride (aq) + water (aq)
Ca(OH)2(aq) + HCl (aq) -> CaCl2(aq) + H2O
Potassium sulfate (aq)+hydrochloric acid (aq) NO REACTION
KCl(aq) + H2SO4(aq) -> K2SO4(aq)+HCl(aq)

11. Copper sulfide(aq)+potassium chloride(aq)->
Copper chloride (aq) + potassium sulfide (aq)
CuCl2(aq) + K2S(aq) NO REACTION

12. The pancreas secretes sodium bicarbonate into the small intestine to neutralize gastric acid. The same thing happens when you have acidity and eat Tums. HCl + NaHCO3 → NaCl + H2CO3
acid soil & rain: CaSO4 & H2O --> Ca(OH)2 (s) & H2SO4