JEE Main 2014 · 12 Apr · Shift 1 · Chemistry Q37

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ChemistrySingle correct+4 / -1Question 37 of 90

The entropy (S°) of the following substances are :

$\ce{CH4}$ (g) 186.2 J K $^{-1}$ mol $^{-1}$
$\ce{O2}$ (g) 205.0 J K $^{-1}$ mol $^{-1}$
$\ce{CO2}$ (g) 213.6 J K $^{-1}$ mol $^{-1}$
$\ce{H2O}$ ( $l$ ) 69.9 J K $^{-1}$ mol $^{-1}$

The entropy change (ΔS°) for the reaction
$\ce{CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l)}$
is :

-312.5

J K

^{-1}

mol

^{-1}

-242.8

J K

^{-1}

mol

^{-1}

-108.1

J K

^{-1}

mol

^{-1}

-37.6

J K

^{-1}

mol

^{-1}

Answer and worked solution

Official answer: B

$\Delta S^\circ=(213.6+2\times69.9)-(186.2+2\times205.0)=353.4-596.2=-242.8\text{ J K}^{-1}\text{mol}^{-1}.$

Topics:Entropy

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JEE Main 2014 · 12 Apr · Shift 1, Chemistry question 37