BITSAT2012ChemistryThermodynamics (C)Actual
In which of the following reactions, standard entropy change ( S ^ ) is positive and standard Gibb's energy change ( G ^ ) decreases sharply with increasing temperature?
Options
- AC (graphite) + 1 2 O ₂( ~g ) CO ( g )
- BCO ( g )+ 1 2 O ₂( ~g ) CO ₂( ~g )
- CMg ( s )+ 1 2 O ₂( ~g ) MgO ( s )
- D1 2 C (graphite) + 1 2 O ₂( ~g ) 1 2 CO ₂( ~g )
Correct answer
A. C (graphite) + 1 2 O ₂( ~g ) CO ( g )
Step-by-step solution
Since, in the first reaction gaseous products are forming from solid carbon hence entropy will increase i.e. S =+ ve . C ( gr .)+ 1 2 O ₂( ~g ) CO ( g ) ; S ^ =+ ve Since, G ^ = H ^ - T S hence the value of G decrease on increasing temperature.