JEE Mains · Chemistry · STD 11 - 5. Thermodynamics and thermochemistry
The difference between \(\Delta H\) and \(\Delta U\) \((\Delta H - \Delta U),\) when the combustion of one mole of heptane \((I)\) is carried out a temperature \(T\) is equal to
- A \(-4\,RT\)
- B \(-3\,RT\)
- C \(3\,RT\)
- D \(4\,RT\)
Answer & Solution
Correct Answer
(A) \(-4\,RT\)
Step-by-step Solution
Detailed explanation
\({C_7}{H_{16}}(l) + 11{O_2}(g) \to 7C{O_2}(g) + 8{H_2}O(l)\) \(\Delta {n_g} = {n_p} - {n_r}\) \( = 7 - 11 = - 4\) \(\because \,\Delta H = \Delta U + \Delta {n_g}RT\) \(\therefore \,\Delta H - \Delta U = - 4\,RT\)
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