Double Replacement Reactions

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

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

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

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

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

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)

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)

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

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