The standard enthalpies of formation of ${Al}_{2} O_{3}$ and $CaO$ are $- 1675 kJ {mol}^{- 1}$ and $- 635 kJ {mol}^{- 1}$ respectively.
For the reaction
$3 CaO + 2 Al \to 3 Ca + {Al}_{2} O_{3}$ the standard reaction enthalpy $Δ_{r} H^{0} =$ ________ $kJ .$
(Round off to the Nearest Integer).

Question

The standard enthalpies of formation of ${Al}_{2} O_{3}$ and $CaO$ are $- 1675 kJ {mol}^{- 1}$ and $- 635 kJ {mol}^{- 1}$ respectively.

For the reaction

$3 CaO + 2 Al \to 3 Ca + {Al}_{2} O_{3}$ the standard reaction enthalpy $Δ_{r} H^{0} =$ ________ $kJ .$

(Round off to the Nearest Integer).

TestHub · Accepted Answer

Given reaction: 3 CaO + Al → Al 2 O 3 + 3 Ca Now, Δ r H ° = ΣΔ f H Products º - ΣΔ f H Reactants º = [ 1 × ( - 1675 ) + 3 × 0 ] - [ 3 × ( - 635 ) + 2 × 0 ] = + 230 kJ mol - 1

Chemistry - Thermochemistry Question with Solution | TestHub

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