JEE Mains · Chemistry · STD 11 - 5. Thermodynamics and thermochemistry
The \((S^o)\) of the following substances are \(CH_4\,(g)\,\,186.2\,JK^{-1}\,mol^{-1}\)
\(O_2\,(g)\,\,205.2\,JK^{-1}\,mol^{-1}\)
\(CO_2\,(g)\,\,213.6\,JK^{-1}\,mol^{-1}\)
\(H_2O\,(g)\,\,69. 9\,JK^{-1}\,mol^{-1}\) The entropy change \((\Delta S^o)\)........\(JK^{-1}\,mol^{-1}\) for the reaction \(CH_4\,(g) + 2O_2\,(g) \to CO_2\,(g) + 2H_2O(l)\) is
- A \(-312.5\)
- B \(-242.8\)
- C \(-108.1\)
- D \(-37.6\)
Answer & Solution
Correct Answer
(B) \(-242.8\)
Step-by-step Solution
Detailed explanation
\(\Delta {S^o} = S_{_{C{O_2}}}^o + 2 \times S_{_{{H_2}O}}^o - (S_{_{C{H_4}}}^o + 2 \times S_{{O_2}}^o)\) \( = (213.6 + 2 \times 69.9) - (186.2 + 2 \times 205.2)\) \( = - 242.8\,J\,{K^{ - 1}}\,mo{l^{ - 1}}\,\)
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