For the allotropic change represented by equation C(diamond) `rarr` C(graphite), the enthalpy change is `DeltaH=-1.89` kJ. If 6g of diamond and 6g of graphite are separately burnt to yield carbon dioxide, the heat liberated in the first case is

Options

A. Less than in the second case by 1.89 kJ
B. More than in the second case by 1.89 kJ
C. Less than in the second case by 11.34 kJ
D. More than in the second case by 0.945 kJ

Answer

D

Explanation

`C_(("graphite"))rarrC_(("diamond")), DeltaH=-1.89 kJ`
`C_(("graphite"))+O_(2)rarrCO_(2), DeltaH=-DeltaH_(1)`
`C_(("diamond"))+O_(2)rarrCO_(2), DeltaH=-DeltaH_(2)`
`(-DeltaH_(1))-(-DeltaH_(2))=1.89 kJ` for 12 g `C_("Diamond")rarrC_("graphite")`
for combustion of 6g, `C_("Diamond")rarrC_("graphite") =-1.89//2=-0.945 kJ`.