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Important Chemical Reactions

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Displacement Reactions
Single Displacement reaction :

When one element displaces another element from a compound and takes its place, the reaction is called a displacement reaction. This is based on reactivity series of the elements .






Reacts with cold water



Most reactive metals


Reacts with acids










Reacts with Oxygen































Most unreactive metals
















Examples of Single Displacement 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 Displacement 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)

Solubility Chart

Solubility of Common Compounds in Water

Negative Ions (Anions) Positive Ions (Cations) Compounds
essentially all    alkali ions soluble*Alkali ions = Li+, Na+, K+, Rb+, Cs+, Fr+
essentially all  hydrogen ion, H+ soluble
essentially all ammonium ion, NH4+ soluble
nitrate, NO3-   essentially all soluble
acetate, CH3COO-  essentially all soluble
chloride, Cl- bromide, Br- iodide, I- 

Ag+, Pb2+, Hg22+, Cu1+  low solubility

all others are soluble

sulfate, SO42-  

Ca2+, Sr2+, Ba2+, Pb2+, Ra2+, Ag+, Hg2+low solubility  

all others soluble

sulfide, S2-   

alkali ions*, H+, NH4+, Be2+, Mg2+, Ca2+, Sr2+, Ba2+, Ra2+   soluble 

all others low solubility

hydroxide, OH-  

 alkali ions*, H+, NH4+, Sr2+, Ba2+, Ra2+   soluble

 all  others  low solubility

phosphate, PO43- , carbonate, CO32-, sulfite, SO32-

alkali ions*, H+, NH4+  low solubility

all others soluble

FeCl 2 (aq)  +  2NaOH  (aq)   Fe(OH) 2  (aq) +  2NaCl (aq) 

Pb(NO3)2  (aq) +   Na2SO4    (aq)    PbSO4 (s)   + 2 NaNO3 (aq)


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