5.2 Displacement Reactions

Learning Goals Learn how to read and use the activity series Learn what is a single displacement reaction and how to create a single displacement reactions Learn what is a double displacement reaction and how to create a double displacement reaction

Classifying Chemical Reactions The new substances, or products, that form during chemical changes will depend on the type of chemical reaction occurring. There are four main types of chemical reactions: 1)Synthesis Reactions 2)Decomposition Reactions 3)Single Displacement Reactions 4)Double Displacement Reactions

Single Displacement Reactions In a single displacement reaction, one element takes the place of (displaces) another element in a compound. There are two general forms of equations for a single displacement reaction: For a single displacement, where A is a metal: For a single displacement, where A is a non-metal:

Example 1 A single displacement reaction involving a metal replacing another metal occurs when copper is placed in an aqueous solution of silver nitrate. copper + silver nitrate  copper(II) nitrate + silver Cu(NO 3 ) 2 (aq) + Ag(s)Cu(s) + AgNO 3 (aq)  Cu(s) + AgNO 3 (aq)  Cu(NO 3 ) 2 (aq) + Ag(s)Cu(s) + 2AgNO 3 (aq)  Cu(NO 3 ) 2 (aq) + 2Ag(s)

Metals differ in their reactivity. The activity series is a list of metals organized according to their chemical reactivity; the most reactive metal appears at the top and the least reactive metal appears at the bottom. A reactive metal will displace or replace a metal in a compound that is below it in the activity series.

Looking back at the previous example: Ag(s) + Cu(NO 3 ) 2 (aq)  Cu(s) + 2AgNO 3 (aq)  Cu(NO 3 ) 2 (aq) + 2Ag(s) Could it be the other way around? No reaction

Example 2 A single displacement reaction involving a metal replacing hydrogen occurs when zinc is placed in an aqueous solution of hydrochloric acid (hydrogen chloride). zinc + hydrochloric acid  zinc chloride + hydrogen ZnCl 2 (aq) + H 2 (g)Zn(s) + HCl(aq)  Zn(s) + 2HCl(aq)  ZnCl 2 (aq) + H 2 (g)

A single displacement reaction involving a non-metal replacing another non-metal occurs when fluorine is placed in an aqueous solution of potassium iodide. fluorine + potassium iodide  potassium fluoride + iodine KF(aq) + I 2 (g)F 2 (g) + KI(aq)  F 2 (g) + 2KI(aq)  2KF(aq) + I 2 (g) Example 3

Double Displacement Reactions In a double displacement reaction, the cations of two different compounds exchange places, forming two new compounds. The general form of the equation is: In this equation, A and C are cations and B and D are anions.

Example An example of a double displacement reaction occurs when barium hydroxide and sodium sulfate are mixed in a solution. barium hydroxide + sodium sulfate  barium sulfate + sodium chloride BaSO 4 (s) + NaOH(aq)Ba(OH) 2 (aq) + Na 2 SO 4 (aq)  Ba(OH) 2 (aq) + Na 2 SO 4 (aq)  BaSO 4 (s) + 2NaOH(aq)

Example The following is a double displacement reaction. Complete and balance the chemical equation. AlCl 3 (aq) + CuNO 3 (aq) 

Homework Textbook: Read Section 5.2 Questions pg 193 # 1, pg 196 # 1 Formal Lab Report Due Thursday!