NEET2005ChemistryThermodynamics (C)Actual
Which of the following pairs of a chemicals reaction is certain to result in a spontaneous reactions?
Options
- AExothermic and increasing disorder
- BExothermic and decreasing disorder
- CEndothermic and increasing disorder
- DEndothermic and decreasing disorder
Correct answer
A. Exothermic and increasing disorder
Step-by-step solution
For spontaneous reaction H =-v e , S =+v e Related Theory When the reaction is exothermic (negative H ) but undergoes a decrease in entropy (negative S) , it is the enthalpy term which favours the reaction. In this case, a spontaneous reaction is dependent upon the TAS term being small relative to the H term, so that G is negative. The freezing of water is an example of this type of process. It is spontaneous only at a relatively low temperature. Above 273 ~K , the larger T S value causes the sign of G to be positi