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Given, `2Fe+(3)/(2)O_(2)toFe_(2)O_(3),DeltaH=-193.4kJ,Mg+(1)/(2)O_(2)to MgO,DeltaH=-140.2kJ` What is the `DeltaH` for the following reaction? `3Mg+Fe_(2)O_(3) to 3MgO+2Fe`A. `-227.2kJ`B. `-272.3kJ`C. `227.2kJ`D. `272.3kJ`

Answer» Correct Answer - A
`2Fe+(3)/(2)O_(2)toFe_(2)O_(3),DeltaH=-193.4kJ` . . (i)
`Mg+(1)/(2)O_(2)toMgO,DeltaH=-140.2kJ` . .. (ii)
On multiplying Eq. (iI) by (3) and subtracting eq. (i) we get the final equation,
`3Mg+Fe_(2)O_(3)to2Fe+3MgO,`
`therefore DeltaH=(-420.6)+(193.4)=-227.2kJ`


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