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The enthalpies of formation of Al(2)O(3)...

The enthalpies of formation of `Al_(2)O_(3)` and `Cr_(2)O_(3)` are `-1596KJ` and `-1134KJ` respectively. `DeltaH` for the reaction
`2Al+Cr_(2)O_(2)rarr2Cr+Al_(2)O_(3)` is

A

`-1365 kJ`

B

`+2730 kJ`

C

`-2730 kJ`

D

`-462 kJ`

Text Solution

Verified by Experts

The correct Answer is:
D
`DeltaH=sumDeltaH_(f)("Products")-sumDeltaH_(f)("reactants")`
`=DeltaH_(f)(Al_(2)O_(3))-DeltaH_(f)(Cr_(2)O_(3))`
[`DeltaH_(f)` of elements in standard state `=0`]
`=-1596 kJ-(-1134 kJ)`
`=1134 kJ-1596kJ=-462 kJ`
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