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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

`-2730` kJ

B

`-462` kJ

C

`-1365` kJ

D

`+2730` kJ

Text Solution

Verified by Experts

The correct Answer is:
B
`2Al+(3)/(2)O_(2)rarrAl_(2)O_(3), DeltaH=-1596 kJ" ....(i)"`
`2Cr+(3)/(2)O_(2)rarrCr_(2)O_(3), DeltaH=-1134 kJ" ....(ii)"`
By (i) - (ii)
`2Al+Cr_(2)O_(3)rarr2Cr+Al_(2)O_(3), DeltaH=-462 kJ`.
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