‘Stability of a crystal is reflected in the magnitude of its melting points'. Comment. Collect melting points of solid water, ethyl alcohol, diethyl ether and methane from a data book. What can you say about the intermolecular forces between these molecules ?

‘Stability of a crystal is reflected in the magnitude of its melting

1.	‘Stability of a crystal is reflected in the magnitude of its melting points'. Comment. Collect melting points of solid water, ethyl alcohol, diethyl ether and methane from a data book. What can you say about the intermolecular forces between these molecules ?
Answer» Solution : The stability of a crystal is reflected in the magnitude of MELTING points i.e., higher the melting point, stronger are the interparticle forces between the constituent particles and hence more is the stability of a crystal. The melting points of the given substances are as FOLLOWS : (i) Solid WATER = 273 K (ii) Ethyl alcohol : 155.7 K (iii) Diethyl ETHER = 156.8 K (iv) Methane = 90.5 K From these data, the magnitude of inter molecular forces are : Solid water > Diethyl ether `gt` Ethyl alcohol `gt` Methane The type of intermolecular forces present are : (i) Solid water `implies` H-bonding (4 H-bonds) (ii) Diethyl ether `implies` dipole-dipole interaction. (iii) Ethyl alcohol `implies`H-bond (3 H-bond) (iv) Methane `implies` London dispersion forces.