Question

Solids and liquid are collectively known as condensed phases.Explain.

Answer 1

SOLIDS AND LIQUIDS HAVE MUCH SMALLER PARTICLES AS COMPARED TO THOSE IN GASES. HENCE THEY ARE COLLECTIVELY KNOWN AS CONDENSED PHASE.

Answer 2

If the ratio of the gas volume to liquid volume is 1000, then the ratio of the distance between the

molecules in the gas to that between those in the l

iquid is the cube root of the volume ratio, that is,

ten.  The molecules of the gas are ten times farther apart on the average than are those of the

liquid.  The distance between molecules in the liquid is roughly equal to the molecular diameter;

hence, in

the gas the molecules are separated by a distance which is, on the average, ten times their

diameter.  This large spacing in the gas compared with that in the liquid results in the

characteristic properties of the gas and the contrast of these properties

with those of the liquid.  

This comes about simply because of the short

-

range nature

of the intermolecular forces, the van

der Waals forces.  The effect of these forces decreases very sharply with increase in distance

between the molecules and falls to an

almost negligible value at distances of four to five times the

molecular diameter.  If we measure the forces by the magnitude of the term a/

2

in the van der

Waals equation, then an increase in volume by a factor by a factor of 1000 in going from liquid to

gas decreases the term by a factor of 10

6

.  Conversely, in the liquid the effect of the van der Waal;s

forces is a million times larger than it is in the ga

s.