Q49 / 150 · MHT CET 2020 (15 Oct Shift 1) · Chemistry

What is the value of $\Delta \mathrm{H}^{\circ}$ for the formation of ethanol from ethene gas and liquid water from following data? (i) $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}_{(1)}+3 \mathrm{O}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{CO}_{2(\mathrm{~g})}+3 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})} \Delta \mathrm{H}^{\circ}=-1368 \mathrm{~kJ}$ (ii) $\mathrm{C}_{2} \mathrm{H}_{4(\mathrm{~g})}+3 \mathrm{O}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{CO}_{2(\mathrm{~g})}+2 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})} \Delta \mathrm{H}^{\circ}=1410 \mathrm{~kJ}$

  • A
    $-1326 \cdot 0 \mathrm{~kJ}$
  • B
    $-4188 \cdot 0 \mathrm{~kJ}$
  • Correct answer
    C
    $-42 \cdot 0 \mathrm{~kJ}$
  • D
    $-2778 \cdot 0 \mathrm{~kJ}$

Solution

Subtract equation (i) from equation (ii) $\therefore \quad \Delta H^{0}=1410-1368=42 \mathrm{~kJ}$

Hence, the correct answer is option: 'C'.

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