The value of `DeltaH_("transition")` of C (graphite) `rarr` C (diamond) is 1.9 kJ/mol at `25^(@)C`. Entropy of graphite is higher than entropy of diamond. This implies that :

Options

A. C (diamond) is more thermodynamically stable than C (graphite) at `25^(@)C`
B. C (graphite) is more thermodynamically stable than C (diamond) at `25^(@)C`
C. diamond will provide more heat on complete combustion at `25^(@)C`
D. `DeltaG_("transition")` of C (diamond) `rarr` C (graphite) is - ve

Answer

B, C, D

Explanation

`C("graphite")rarrC("diamond")`
`DeltaG = DeltaH - TDeltaS`
`=1.9 -298 (-ve)=+ve`
Graphite is more stable than diamond thermodynamically
`Delta_(r)H=(Delta_(C)H)_(G)-(Delta_(C)H)_(D),(Delta_(C)H)_(G)=-x(Delta_(C)H)_(D)=-y`
`1.9 =-x+yimplies y=1.9 +x`
Diamond provides more heat on complete combustion in comparison of graphite.