question_answer

Standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are\[-382.64\,KJ\,mo{{l}^{-1}}\] and \[-145.6\,J{{K}^{-1}}\,mo{{l}^{-1}},\] respectively. Standard Gibbs energy change for the same reaction at 298 K is:                                                                                                                                     [AIPMT (S) 2004]

A)  \[-2221.1\,\,kJ\,\,mo{{l}^{-1}}\]

B)       \[-339.3\,\,kJ\,\,mo{{l}^{-1}}\]

C)  \[-\,439.3\text{ }kJ\text{ }mo{{l}^{-1}}\]

D)       \[-523.2\,kJ\,mo{{l}^{-1}}\]

Correct Answer: B

Solution :

For the oxidation of ammonia at 298 K the standard enthalpy change  and standard entropy change  are and respectively. The relation- ship of Gibbs free energy  withand  is represented in form of following equation.

Given that

or