Comment on the spontaneity of a reaction at constant temperature and pressure in the following cases. (i)DeltaH lt 0 and DeltaS gt 0 (ii) DeltaH gt0 and Delta S lt 0(iii) DeltaH lt 0 and DeltaS lt 0 (iv)DeltaH gt 0 andDeltaS gt 0

Comment on the spontaneity of a reaction at constant temperature and p

1.	Comment on the spontaneity of a reaction at constant temperature and pressure in the following cases. (i)DeltaH lt 0 and DeltaS gt 0 (ii) DeltaH gt0 and Delta S lt 0(iii) DeltaH lt 0 and DeltaS lt 0 (iv)DeltaH gt 0 andDeltaS gt 0
Answer» Solution :(i) Both energy factor and randomness factor FAVOUR the PROCESS. Hene, reaction will be always spontaneous. (II)Both factors opposes the process. Hence, reaction would be always non-spontaneous. (iii) Energy factor favour but randomness factor opposes. For process to be spontaneous , opposing factor should be smaller, i.e., `T DELTAS lt DeltaH`. Hence, reaction is spontaneous at low temperature ANDNON- spontaneous at high temperature. (iv) Energy factor opposes but randomness factor . For spontaneity, `T DeltaS gt DeltaH`. Hence, reaction is spontaneous at high temperature and non-spontaneous at low temperature.