4.6 DOUBLE DISPLACEMENT REACTIONS

Involves both elements in different compounds displacing each other or exchanging places. The metals switch places and the non-metals switch places Analogy - two couples dancing and they switch partners

The general equation for a double displacement reaction is: AB + XY  AY + XB Examples: Complete and Balance the reactions! FeCl3 + Na2S      AgNO3 + NaCl  Pb(NO3)2 + KI  `

Types of Double Displacement Reactions 1) Production of a Precipitate A precipitate is an insoluble compound that forms when two clear liquids are mixed Depends on the solubility of the chemicals involved Chemicals with low solubility tend to form precipitates Useful for removing harmful ions

Separating a precipitate: A filtration apparatus is designed to separate a precipitate from a liquid. The filtrate can be allowed to evaporate, revealing any more soluble compounds.

3) The reaction in neutralized 2) Production of a gas Gas is one of the products that is formed 3) The reaction in neutralized Also called an acid base reaction The products formed are neither acidic or basic Products are usually water and a “salt” (ionic compound)

Solubility Solute: a substance that dissolves in a solvent Solvent: the substance in which a solute will dissolve Solubility: a property of a substance where the maximum amount of solute that will dissolve in a known quantity of solvent at a set temperature and pressure

if a chemical is very soluble it will stay in solution if a chemical is not very soluble it will sometimes come out of solution in the form of a solid called a precipitate the precipitate will get the subscript symbol (s) which stands for solid  if a chemical in not very soluble it will sometimes come out of solution in the form of a gas the gas will get the subscript symbol (g) which stands for gas

There is a solubility table on page 173 of your text 1. Find the anion part in column 2 2. look at column 2 and see if your cation part is in the list of exceptions 3. If you do have an exception, and it is in the soluble row, a precipitate WILL form 4. If you do have an exception, and it is in the insoluble row, NO precipitate will form

Examples! Ex. 1 Will potassium chloride precipitate out of solution? Ex. 2 Will ammonium sulfate precipitate out of solutions? Ex. 3 Will Barium sulfate precipitate out of solutions?

Ex. 4 Predict the products formed when calcium chloride and sodium carbonate are mixed. Ex. 4 Predict the products formed when sodium sulfide solution and hydrochloric acid are placed in a beaker together.

For the following ions, determine what you could use to precipiate it out of a water sample. A) Lead (II) B) Mercury (I) C) Copper (I)