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COMEDK2012ChemistryThermodynamics (C)

The heat of formation of H ₂ O (l) is -286 ~kJ . The heat of formation of H ₂ O ( g ) is likely to be

Options

  1. A-286 ~kJ
  2. B+286 ~kJ
  3. C-34 l kJ
  4. D-242.8 ~kJ

Correct answer

D. -242.8 ~kJ

Step-by-step solution

The heat of formation of H ₂ O ( g ) will be less than the heat of formation of H ₂ O (l) , as heat of condensation is not included in formation of H ₂ O in gases state i.e. array lr & H ₂(g)+ 1 2 O ₂(g) H₁ H ₂ O (g) H₂ H ₂ O (l) & | H_ f_ ( H ₂ O )_ l |= | H₁+ H₂ |=286 ~kJ But & | H_ f_ ( H ₂ O )_ g = | H₁ < 286 ~kJ & H_ f_ ( H ₂ O ) g =-242.8 ~kJ array

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