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KCET2013ChemistryThermodynamics (C)

Given thermochemical equation, 2 H ₂(g)+ O ₂(g) 2 H ₂ O (l) ; H=-571.6 ~kJ . Heat of decomposition of water is

Options

  1. A-571.6 ~kJ
  2. B+571.6 ~kJ
  3. C-1143.2 ~kJ
  4. D+285.8 ~kJ

Correct answer

D. +285.8 ~kJ

Step-by-step solution

Given (i) 2 H ₂(g)+ O ₂(g) 2 H ₂ O ; H =-571.6 ~kJ At H ₂ O (I) H ₂(g)+ 1 2 O ₂(g) ; H=? If reaction (i) is reversed and divided by 2 , the sign of H changes, i.e., H for decomposition of water =+ 571.6 2 =285.8 ~kJ

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