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  • The standard enthalpies of formation of Al2O3 and CaO are and <img alt="-635 \; kJ\; mol^{-1}" src="/latex-image/?-635%20%5

The standard enthalpies of formation of Al2O3 and CaO are -1675 \; kJ\; mol^{-1} and -635 \; kJ\; mol^{-1} respectively. For the reaction 3 \mathrm{CaO}+2 \mathrm{Al} \rightarrow 3 \mathrm{Ca}+\mathrm{Al}_{2} \mathrm{O}_{3} the standard reaction enthalpy \Delta _{r}H^{0}=___________kJ. (Round off to the Nearest Integer).
Option: 1 230
Option: 2 -
Option: 3 -
Option: 4 -

Answers (1)

best_answer

Given reaction is:

3 \mathrm{CaO}+\mathrm{Al} \rightarrow \mathrm{Al}_{2} \mathrm{O}_{3}+3 \mathrm{Ca}

We know the standard reaction enthalpy formula-

\Delta \mathrm{H}_{\mathrm{f}}^{0}=\Delta \mathrm{H}_{\mathrm{f}}^{0} \text { (Products) }-\Delta \mathrm{H}_{\mathrm{f}}^{0} \text { (Reactants) }

=\Delta \mathrm{H}_{\mathrm{f}}^{0}\left(\mathrm{Al}_{2} \mathrm{O}_{3}\right)-3 \times \Delta \mathrm{H}_{\mathrm{f}}^{0}(\mathrm{CaO})

= – 1675 –3 (–635)

= 230 kJ

Ans = 230

Posted by

Kuldeep Maurya

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