The Foundations of Chemistry

EXAMPLE 4-5 Displacement Reaction

A large piece of zinc metal is placed in a copper(II) sulfate, CuSO 4 , solution. The blue solu-

tion becomes colorless as copper metal falls to the bottom of the container. The resulting

solution contains zinc sulfate, ZnSO 4. Write balanced formula unit, total ionic, and net ionic

equations for the reaction.

Plan

The metals zinc and copper are notionized or dissociated in contact with H 2 O. Both CuSO 4

and ZnSO 4 are soluble salts (solubility guideline 5), and so they are written in ionic form.

Solution

Zn(s)
CuSO 4 (aq)88nCu(s)
ZnSO 4 (aq)

Zn(s)
[Cu^2 
(aq)
SO 42 (aq)]88nCu(s)
[Zn^2 
(aq)
SO 42 (aq)]

Zn(s)
Cu^2 
(aq)88nCu(s)
Zn^2 
(aq)

In this displacement reaction,the more active metal, zinc, displaces the ions of the less active

metal, copper, from aqueous solution.

You should now work Exercise 58.

A strip of zinc metal was placed in a
blue solution of copper(II) sulfate,
CuSO 4. The copper has been
displaced from solution and has
fallen to the bottom of the beaker.
The resulting zinc sulfate, ZnSO 4 ,
solution is colorless.

148 CHAPTER 4: Some Types of Chemical Reactions

TABLE 4-12 Activity Series of Some Elements

Common Common

Element Reduced Form Oxidized Forms

Li Li Li


KKK


Ca Ca Ca^2 


Na Na Na


Mg Mg Mg^2 


Al Al Al^3 


Mn Mn Mn^2 


Zn Zn Zn^2 


Cr Cr Cr^3 
, Cr^6 


Fe Fe Fe^2 
, Fe^3 


Cd Cd Cd^2 


Co Co Co^2 


Ni Ni Ni^2 


Sn Sn Sn^2 
, Sn^4 


Pb Pb Pb^2 
, Pb^4 


H (a nonmetal) H 2 H


Sb (a metalloid) Sb Sb^3 


Cu Cu Cu
, Cu^2 


Hg Hg Hg 22 
, Hg^2 


Ag Ag Ag


Pt Pt Pt^2 
, Pt^4 


Au Au Au
, Au^3 

Displace hydrogen from nonoxidizing acids

Displace hydrogen from steam

Displace hydrogen from cold water

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