1. Tardigrade
  2. Question
  3. Chemistry
  4. Standard molar enthalpies of formation of CaCO 3( s ) CaO ( s ) and CO 2( g ) are -1206 ⋅ 92 kJ mol -1,-635 ⋅ 09 kJ mol -1 and -393 ⋅ 51 kJ mol -1 respectively. The Δ Hr for decomposition of CaCO 3( s ) is

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Q. Standard molar enthalpies of formation of $CaCO _{3( s )} CaO _{( s )}$ and $CO _2( g )$ are $-1206 \cdot 92 \,kJ \,mol ^{-1},-635 \cdot 09\, kJ \,mol ^{-1}$ and $-393 \cdot 51 \,kJ\, mol ^{-1}$ respectively. The $\Delta H_r$ for decomposition of $CaCO _{3( s )}$ is

COMEDKCOMEDK 2014Thermodynamics

Solution:

$CaCO _{3( s )} \longrightarrow CaO _{( s )}+ CO _{2( g )}$
$ \Delta_r H^{\circ} =\Delta_f H^{\circ}( CaO )+\Delta_f H^{\circ}\left( CO _2\right)-\Delta_f H^{\circ}\left( CaCO _3\right) $
$=(-635.09)+(-393.51)-(-, 1206.92) $
$=178 \cdot 3 \,kJ \,mol ^{-1} $