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Fajan Rule: Solved examples

Fajan Rule

source : microamaze blogspot.com

Fajan Rule: Solved examples

Q 5: Write decreasing order of Covalent character in LiF , LiCl ,LiBr .

Solution :  LiBr > LiCl > LiF

Reason : Bigger is the anion, greater is the covalent character.

Q 6: LiCl is soluble in organic solvents like alcohol while NaCl is not ?

Solution :  In LiCl , more covalent character is present due to small cation Li+. Smaller is the cation, more is the covalent character. Covalent compounds are soluble in organic solvents.

Q 7:  Write decreasing order of melting point and increasing order of covalent character  in  CaF2 , CaCl2 ,CaBr2 & CaI2

Solution :  CaF2 > CaCl2 >CaBr2 > CaI2

Decreasing order of melting point

CaF2 < CaCl2 <CaBr2 < CaI2

increasing order of covalent character

Reason : Bigger is the anion, greater is the covalent character. CaF2 is ionic ,so its melting point is high.

Q 8: Write  decreasing order of melting point and increasing order of covalent character in BaCl2 , CaCl2 , MgCl2 & BeCl2

Solution : BaCl2 > CaCl2 > MgCl2 > BeCl2

increasing order of covalent character

BaCl2 > CaCl2 > MgCl2 > BeCl2

decreasing order of melting point

Reason :  Smaller is the cation, more is the covalent character so BeCl2 is more covalent.  Melting point of covalent compound is less than electrovalent compound.

Q 9:  CuCl  is more covalent than NaCl . why ?

Solution :  According to Fajan Rule, Effective nuclear charge in cation having s2, p6,d10 configuration is greater than s2p6 configuration therefore cation having s2,p6, d10 configuration is more covalent.

Hence CuCl (configuration s2, p6,d10) is more covalent than NaCl.

Q 10:  LiCl  is more soluble in pyridine than in H2O . why ?

Solution : According to  Fajan Rule Smaller is the cation, greater is the covalent character.

Hence LiCl has covalent character thus it is more soluble in organic solvents like pyridine than H2O.


 

Saroj Bhatia: Dr. Saroj Bhatia is an Ph.D in chemistry who has been teaching chemistry for over a decade. Currently she is a respected principal of a renowned college in her hometown. She took this medium for online users. Her proudest achievement is helping people learn chemistry.
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