1. Tardigrade
  2. Question
  3. Chemistry
  4. For combustion of one mole of magnesium in an open container at 300 K and 1 bar pressure, Δ C H Θ =-601.70 kJ mol -1, the magnitude of change in internal energy for the reaction is KJ(Nearest integer) (Given: R =8.3 J K -1 mol -1 )

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Q. For combustion of one mole of magnesium in an open container at $300 \,K$ and $1$ bar pressure, $\Delta_{ C } H ^{\Theta}$ $=-601.70\, kJ \,mol ^{-1}$, the magnitude of change in internal energy for the reaction is ____$KJ$(Nearest integer) (Given $: R =8.3 \,J K ^{-1} \,mol ^{-1}$ )

JEE MainJEE Main 2022Thermodynamics

Solution:

$ Mg ( s )+\frac{1}{2} O _{2}( g ) \rightarrow MgO ( s ) $
$\Delta H =\Delta U +\Delta n _{ g } RT$
$-601.70 \times 10^{3}=\Delta U -\frac{1}{2} \times 8.3 \times 300 $
$-601.70 \,kJ =\Delta U -1.245\, kJ$
$\Delta U =-600.455\, kJ$
Ans. $600$