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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 -1596 kJ and -1134 kJ respectively. `DeltaH` for the reaction, `2Al+Cr_(2)O_(3)to2Cr+Al_(2)O_(3)` is

A

`-2730kJ`

B

`-462kJ`

C

`-1365kJ`

D

`+2730kJ`

Text Solution

Verified by Experts

The correct Answer is:
B
According to question
`2Al+(3)/(2)O_(2)toAl_(2)O_(3),`
`DeltaH=-1596kJ` . . (1)
`2Cr+(3)/(2)O_(2)toCr_(2)O_(3)`,
`DeltaH=-1134kJ` . . (2)
From (1)-(2)
`2Al-2Cr=Al_(2)O_(3)-Cr_(2)O_(3),DeltaH=-462kJ`
or `2Al+Cr_(2)O_(3)=Al_(2)O_(3)+2Cr,DeltaH=-462kJ`.
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