JEE Mains · Chemistry · STD 11 - 5. Thermodynamics and thermochemistry
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 \(3 CaO +2 Al \rightarrow 3 Ca + Al _{2} O _{3}\) the standard reaction enthalpy \(\Delta_{ r } H ^{0=}\) .......... \(kJ\). (Round off to the Nearest Integer).
- A \(220\)
- B \(240\)
- C \(230\)
- D \(250\)
Answer & Solution
Correct Answer
(C) \(230\)
Step-by-step Solution
Detailed explanation
Given reaction: \(3 CaO + Al \rightarrow Al _{2} O _{3}+3 Ca\) Now, \(\Delta_{ r } H ^{\circ}=\Sigma \Delta_{ f } H _{\text {Products }}^{\circ}-\Sigma \Delta_{ f } H _{\text {Reactants }}^{\circ}\) \(=[1 \times(-1675)+3 \times 0]-[3 \times(-635)+2 \times 0]\)…
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