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TS EAMCET · Chemistry · Thermodynamics (C)

The enthalpies of formation of gaseous \(\mathrm{N}_2 \mathrm{O}\) and \(\mathrm{NO}\) at \(298 \mathrm{~K}\) are 82.0 and \(90.0 \mathrm{KJ} \mathrm{mol}^{-1}\) respectively. The enthalpy change of the reaction \(\mathrm{N}_2 \mathrm{O}(\mathrm{g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow\) \(2 \mathrm{NO}(\mathrm{g})\) is

  1. A \(-74 \mathrm{~kJ}\)
  2. B +98 kJ
  3. C +89 kJ
  4. D -47 kJ
Verified Solution

Answer & Solution

Correct Answer

(B) +98 kJ

Step-by-step Solution

Detailed explanation

\[ \Delta \mathrm{H}_{\mathrm{r}}^{\circ}=\left[2 \Delta \mathrm{H}_{\mathrm{f}}^{\circ}(\mathrm{NO})\right]-\left[\Delta \mathrm{H}_{\mathrm{f}}^{\circ}\left(\mathrm{N}_2 \mathrm{O}\right)+\frac{1}{2} \Delta \mathrm{H}_{\mathrm{f}}^{\circ}\left(\mathrm{O}_2\right)\right] \]…