Predict the sign of entropy change in each of the following : (i) H_(2) (at 298 K, 1 atm ) rarr H_(2) at 298 K, 10 atm) (ii) H_(2)O(at 298K, 1 atm )rarr H_(2)O ( at 330K, 1atm) (iii) 2NH_(4)NO_(3)(s) rarr 2N_(2)(g)+4H_(2)O(g) +O_(2)(g) (iv)Crystallization of copper sulphatefrom its saturated solution. (v) 2SO_(2)(g) +O_(2)(g) hArr 2SO_(3)(g)

Predict the sign of entropy change in each of the following : (i) H_(

1.	Predict the sign of entropy change in each of the following : (i) H_(2) (at 298 K, 1 atm ) rarr H_(2) at 298 K, 10 atm) (ii) H_(2)O(at 298K, 1 atm )rarr H_(2)O ( at 330K, 1atm) (iii) 2NH_(4)NO_(3)(s) rarr 2N_(2)(g)+4H_(2)O(g) +O_(2)(g) (iv)Crystallization of copper sulphatefrom its saturated solution. (v) 2SO_(2)(g) +O_(2)(g) hArr 2SO_(3)(g)
Answer» Solution :Entropy isa measure of randomness or disorder of a system. If randomness increases, entropy increases. (i) GAS at lower pressure has greater randomness than at high pressure ( compressed gas) at the sametemperature. Hence, entropy decreases, i.e., `DELTA S ` is -ve. (ii) Molecules at highertemperaturehave greater randomness at the same pressure . Hence, `Delta S` is `+` ve . (iii) GASEOUS moleculeshave greater randomness than the solid . Hence, `Delta S` is `+ ` ve. (iv) `CuSO_(4)` crystals have ordered ARRANGEMENT whereas ionsin the soluiton have greater randomness. Hence, `Delta S` is `-` ve. (v) There are 3 MOLES of two different gaseous reactants which have greater randomness than 2 moles of the only gaseous product, `SO_(3)` . Hence, randomness decrease, i.e., `Delta S`is `-` ve.