Chemical Thermodynamics Question 372

Question: The $ ( S{}^\circ ) $ of the following substances are:

$ CH_4( g )186.2J{{K}^{-1}}mo{{l}^{-1}} $

$ O_2( g )205.2J{{K}^{-1}}mo{{l}^{-1}} $

$ CO_2( g )213.6J{{K}^{-1}}mo{{l}^{-1}} $

$ H_2O( g )69.9.J{{K}^{-1}}mo{{l}^{-1}} $

The entropy change $ ( \Delta {{S}^{{}^\circ }} ) $ for the reaction $ CH_4(g)+2O_2(g)\to CO_2(g)+2H_2O(l) $ is:

Options:

A) $ -312.5J,{{K}^{-1}}mo{{l}^{-1}} $

B) $ -242.8J,{{K}^{-1}},mo{{l}^{-1}} $

C) $ -108.1J,{{K}^{-1}},mo{{l}^{-1}} $

D) $ -37.6J{{K}^{-1}}mo{{l}^{-1}} $

Show Answer

Answer:

Correct Answer: B

Solution:

  • $ \Delta S{}^\circ =S{{{}^\circ } _{CO_2}}+2\times S{{{}^\circ } _{H_2O}}-(S{{{}^\circ } _{CH_4}}+2\times S{{{}^\circ } _{O_2}}) $

$ =( 213.6+2\times 69.9 )-( 186.2+2\times 205.2 ) $

$ =-242.8J{{K}^{-1}},mo{{l}^{-1}}. $



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक