Question

Without referring to a data table, rank the following compounds by standard molar entropy. . Highest S HF(g) Ne(g) F2(g) Lowest S

Answer 1

Ans 1 :

Entropy is the degree of randomness or disorderness of the system . Larger sized gaseous molecules have larger standard molar entropy and smaller sized gaseous molecules have a smaller standard molar entropy.

So here , the ranking of compounds in order of highest to lowest standard molar entropy will be :

F2 (g)

Ne (g)

HF (g)

Ans 2 : Two choices are correct :

2NH3 (g) = N2 (g) + 3H2 (g)

CH4 (g) + 2H2O (l) = CO2 (g) + 4H2 (g)

The reactions that have a negative value of gibbs free energy change are energetically favourable reactions. So if the entropy change of a reaction is positive , it is likely to be product favoured reaction.