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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) rarr Al_(2)O_(3), Delta H= -1596kJ` ..(i)
`2Cr + (3)/(2) O_(2) rarr Cr_(2)O_(3), Delta H= -1134kJ` ...(ii)
By (i) - (ii)
`2Al + Cr_(2)O_(3) rarr 2Cr + Al_(2)O_(3), Delta H = -462kJ`
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