1. Tardigrade
  2. Question
  3. Chemistry
  4. The difference between Δ H and Δ U (Δ H- Δ U), when the combustion of one mole of heptane (I) is carried out at a temperature T, is equal to:

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Q. The difference between $\Delta H$ and $\Delta U (\Delta H- \Delta U)$, when the combustion of one mole of heptane (I) is carried out at a temperature $T$, is equal to:

JEE MainJEE Main 2019Thermodynamics

Solution:

$C _7 H _{16}(\ell)+11 O _2( g ) \longrightarrow 7 CO _2( g )+8 H _2 O (\ell)$
$\Delta ng = np - nr =7-11=-4$
$\because \Delta H=\Delta U+\Delta n_g R T$
$\therefore \Delta H-\Delta U=-4 R T$