Question

For the reaction
`C_(3)H_(8)(g)+5O_(2)rarr3CO_(3)(g)+4H_(2)O(l)`
at constant temperature, `DeltaH-DeltaU` is
A. `+3RT`
B. `-RT`
C. `+RT`
D. `-3RT`

Answer 1

Correct Answer - D
For the reaction
`C_(3)H_(8)(g) + 4O_(2)(g) to 3CO_(2)(g) + 4H_(2)O(l)`
`Deltan_(g)` =number of gaseous moles of products -number of gaseous moles of reactants
`=3-6=-3`
`therefore DeltaH=DeltaE+ DeltanRT`
or `DeltaH-Delta E=DeltanRT`
`therefore DeltaH-DeltaE=-3RT`