Answer
Verified
396.6k+ views
Hint: When molecules fit perfectly and closely in a crystal lattice, the packing efficiency increases, and when molecules are closely fit in a lattice, the number of molecules and energy of crystal lattice both increases.
Complete answer:
Molecular symmetry has an immense effect on the melting properties and solubility of organic compounds. As a rule, symmetrical molecules in crystalline form are known to have higher melting points and show lower solubilities compared with molecules of similar structure but having lower symmetry. Symmetry in a molecule gives it a positive amount of residual entropy in the solid phase. This means that the entropy of a crystal having symmetric molecules is greater than the entropy of a crystal of a similar , but non-symmetric molecule.
The more symmetrical the compounds are , the easier it will be to accommodate in lattice and the fewer spaces there will be between the molecules. Symmetric structure imparts better packing.
o-dichlorobenzene and m-dichlorobenzene do not possess symmetry , therefore they will not be efficiently packed, however, this is not the case with p-dichlorobenzene.
p-dichlorobenzene exhibits symmetry, which helps it in better packing efficiency. In crystal lattice, para isomer fits more closely as compared to meta and ortho isomer. And because of this reason, more energy is required to break the crystal lattice of para isomers, and lesser energy is required to break the crystal of meta and ortho isomers.
Hence, para-dichlorobenzene has a higher melting point than meta and ortho dichlorobenzene.
Note: Melting point of p-dichlorobenzene is 323K and boiling point is 448K. And in comparison to that, the melting point of meta-dichlorobenzene is 249K boiling point is 446K and , melting point of ortho-dichlorobenzene is 256K boiling point is 443K. You will notice that boiling points do not have such variations.
Complete answer:
Molecular symmetry has an immense effect on the melting properties and solubility of organic compounds. As a rule, symmetrical molecules in crystalline form are known to have higher melting points and show lower solubilities compared with molecules of similar structure but having lower symmetry. Symmetry in a molecule gives it a positive amount of residual entropy in the solid phase. This means that the entropy of a crystal having symmetric molecules is greater than the entropy of a crystal of a similar , but non-symmetric molecule.
The more symmetrical the compounds are , the easier it will be to accommodate in lattice and the fewer spaces there will be between the molecules. Symmetric structure imparts better packing.
o-dichlorobenzene and m-dichlorobenzene do not possess symmetry , therefore they will not be efficiently packed, however, this is not the case with p-dichlorobenzene.
p-dichlorobenzene exhibits symmetry, which helps it in better packing efficiency. In crystal lattice, para isomer fits more closely as compared to meta and ortho isomer. And because of this reason, more energy is required to break the crystal lattice of para isomers, and lesser energy is required to break the crystal of meta and ortho isomers.
Hence, para-dichlorobenzene has a higher melting point than meta and ortho dichlorobenzene.
Note: Melting point of p-dichlorobenzene is 323K and boiling point is 448K. And in comparison to that, the melting point of meta-dichlorobenzene is 249K boiling point is 446K and , melting point of ortho-dichlorobenzene is 256K boiling point is 443K. You will notice that boiling points do not have such variations.
Recently Updated Pages
Basicity of sulphurous acid and sulphuric acid are
Three beakers labelled as A B and C each containing 25 mL of water were taken A small amount of NaOH anhydrous CuSO4 and NaCl were added to the beakers A B and C respectively It was observed that there was an increase in the temperature of the solutions contained in beakers A and B whereas in case of beaker C the temperature of the solution falls Which one of the following statements isarecorrect i In beakers A and B exothermic process has occurred ii In beakers A and B endothermic process has occurred iii In beaker C exothermic process has occurred iv In beaker C endothermic process has occurred
What is the stopping potential when the metal with class 12 physics JEE_Main
The momentum of a photon is 2 times 10 16gm cmsec Its class 12 physics JEE_Main
How do you arrange NH4 + BF3 H2O C2H2 in increasing class 11 chemistry CBSE
Is H mCT and q mCT the same thing If so which is more class 11 chemistry CBSE
Trending doubts
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Two charges are placed at a certain distance apart class 12 physics CBSE
Difference Between Plant Cell and Animal Cell
What organs are located on the left side of your body class 11 biology CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
The planet nearest to earth is A Mercury B Venus C class 6 social science CBSE
The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths
What is BLO What is the full form of BLO class 8 social science CBSE