Single Replacement Reactions :
When one element displaces another element from a compound and takes its place, the reaction is called a Single Replacement reaction. This is based on reactivity series of the elements .
Examples of Single Replacement Reactions
Less reactive metal can not displace more reactive metal from its compounds .
Zn (s)+ CuSO4 (aq)  ZnSO4 (aq) + Cu(s)
Color changes from bluish green to colorless.
Zn is more reactive than Cu
ZnSO4 (aq) + Cu(s) No reaction
Cu is more reactive than Zn
Fe (aq)+ CuSO4 (aq) FeSO4(aq) +Cu(s)
Color of the solution changes from blue to light green .
Mg(s) + ZnCl2(aq) MgCl2(aq)+Zn (s)
2KI(aq) + Cl 2 (g)2KCl(aq) + I 2 (s)
Zn (s)+ MgCl2(aq) no reaction
2K(s)+2H2O 2 KOH(aq) + H2(g)
2 Na(s) +2H2O(l) Ca(OH)2 (aq)+ H2(g)
Mg (s)+H2O (aq)Mg(OH)2 (aq)+H2 (g)
Fe(s)+ 4H2O(l) Fe3O4(aq)+4H2(aq)
2K(s) + 2HCl(aq) 2 KCl (aq)+H2 (g)
Violent reaction with Cold dilute acid
Zn(s)+2HCl(aq) ZnCl2(aq)+H2(aq)
Reacts Vigorously with Cold dilute acid
Fe(aq)+2HCl(aq) FeCl2+H2
Reacts Slowly quietly with Cold dilute acid
Pb (aq)+ HCl(aq) PbCl 2 (aq)+H2 (aq)
Reacts with Hot Conc acid
Double Displacement Reaction :
A reaction in which the constituent of two compounds mutually exchange their ionic radicals to form two different compounds is called a double decomposition reaction.
Examples of Double Replacement Reactions
Na2SO4 (aq)+ CaCl2 (aq) CaSO4 (aq)+ 2 NaCl (aq)
Precipitation reaction : In aqueous medium compounds react to form an insoluble residue as one of the products.
NaCl (aq) + AgNO 3 (aq) AgCl (s) + NaNO3
Pb (NO3)2 (aq) + Na2SO4 (aq) PbSO4 (S) + 2NaNO3 (aq)
FeCl2 (aq) + 2NaOH (aq) Fe (OH)2 (S)+ 2NaCl (aq)
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