Double Replacement Reactions

Definition Double Replacement is a reaction in which a compound (or solution) and a compound (or solution) yield a new compound and a new solution (or compound) The reactants are two compounds (or two solutions, or one of each) and the products are a different compound and different solution (usually)

Generic Word Equation Compound + Solution yield New compound + New solution Solution + Solution yield New compound + New solution Compound + Compound yield New compound + New compound Must use the Solubility Chart to check to make sure that it does occur. One of the products MUST be a compound.

IMPORTANT Must use the Solubility Chart to check to make sure that it does occur. One of the products MUST be a compound. This means that one of the products must be a solid, liquid, or a gas.

Algebraic Equation AY + BZ  BY + AZ

Examples Sodium Chloride (s) + Copper (II) Nitrate (aq) Sodium Nitrate( ) + Copper (II) Chloride ( ) The Species in the reactants can be either (s) or (aq) It is hard to get two solids to react! Why? Does this work? Why?

No, NR (No Reaction) Sodium Chloride (s) + Copper (II) Nitrate (aq) Sodium Nitrate( aq) + Copper (II) Chloride (aq ) NR, because the products are both (aq) Why does the Copper have the roman numerals?

Examples Zinc Iodide(aq) + Potassium Carbonate (aq) Zinc Carbonate( ) + Potassium Iodide( ) The Species in the reactants can be either (s) or (aq) It is hard to get two solids to react! Why? Does this work? Why?

Yes, DR (Double Replacement) Zinc Iodide(aq) + Potassium Carbonate (aq) Zinc Carbonate( s ) + Potassium Iodide( aq ) There is a solid produced. The solid is called a precipitate. If you are not part of the solution, then you are part of the precipitate.  Why are there no Roman Numerals?

Examples Sodium Hydroxide(aq) + Hydrocloric Acid(aq) Sodium Chloride( ) + Water( )(Hydrogen Hydroxide) The Species in the reactants can be either (s) or (aq) It is hard to get two solids to react! Why? Does this work? Why?

Yes, DR Hydrogen Hydroxide is just water. (H- OH) Sodium Hydroxide(aq) + Hydrocloric Acid(aq) Sodium Chloride( aq ) + Water( l ) (Hydrogen Hydroxide) Hydrogen Hydroxide is just water. (H- OH) Acids are going to be tough because it is not sodium acid and Hydrochloric hydroxide as the products. You need to know the Acid formulas and the cations and anions. Why are there no roman numerals?

Examples Lead (II) Carbonate (s) + Nitric Acid(aq) Lead (II) Nitrate ( ) + Carbonic Acid( ) The Species in the reactants can be either (s) or (aq) Why is it easier to get two solutions to react? Does this work? Why?

Yes, DR Lead (II) Carbonate (s) + Nitric Acid(aq) Lead (II) Nitrate ( aq ) + Carbonic Acid( aq ) Acids are going to be tough because it is not sodium acid and Hydrochloric hydroxide as the products. You need to know the Acid formulas and the cations and anions. WAIT! WHAT!!

Lets look at that again. Lead (II) Carbonate (s) + Nitric Acid(aq) Lead (II) Nitrate ( aq ) + Carbonic Acid( aq ) How can that be a DR when the two products are both aqueous? Well….

Lets look at that again. Lead (II) Carbonate (s) + Nitric Acid(aq) Lead (II) Nitrate ( aq ) + Carbonic Acid( aq ) What happens to carbonic acid? Carbonic Acid  ?

Lets look at that again. Lead (II) Carbonate (s) + Nitric Acid(aq) Lead (II) Nitrate ( aq ) + Carbonic Acid( aq ) Carbonic Acid (aq)  Carbon dioxide (g) + water (l) So this does occur because one product goes right into another reaction. What type of Reaction?

Lets look at that again. Lead (II) Carbonate (s) + Nitric Acid (aq) Lead (II) Nitrate ( aq ) + Carbon dioxide( g) + Water (l) This reaction produces a gas. Why does the Lead have roman numerals?

What is important to remember? Use the Solubility Chart. One of the products must be a compound! In order for a product to be a compound it must be a solid, liquid, or gas. Others?

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