Justify the followingstatement : (a)An exothermic reaction isalways thermodynamicallyspontaneous. (b) The entropyof a substance increaseson going from liquidto vapour state at any temperature.

Justify the followingstatement : (a)An exothermic reaction isalways t

1.	Justify the followingstatement : (a)An exothermic reaction isalways thermodynamicallyspontaneous. (b) The entropyof a substance increaseson going from liquidto vapour state at any temperature.
Answer» Solution :(a) EXOTHERMIC REACTIONS are generally thermodynamically spontaneous becauseeven if it is accompaniedby decrease of randomness ( e.g.,in the condensation of a gas or solidification OFA liquid), the heatreleasedis absorbed by the surroundings so that the entropyof the surroundings increases to such an EXTENT that `DeltaS_("total")` is positive. (b) The molecules in the vapour state have greater freedom of MOVEMENT and hence greater randomness than those in the liquid state. Hence, entropy increases in goingfrom liquidto vapour state.