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Hydrogen Peroxide Decomposition

SwollBoyMax
in Inorganic Chemistry

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Write the balanced equation for the decomposition of hydrogen peroxide into water and oxygen gas.

a. 2H2O2 → 2H2O + O2

Use Hess’ Law to calculate the net energy released.  Then calculate the energy in kJ/ mol—this will be the theoretical value:

H2 + ½ O2 → H2O ΔH = -286 kJ/ mol

H2 + O2     → H2O2 ΔH = -191 kJ/ mol

H2O2 + H2 + ½ O2 → H2 + O2 + H2O    H= -95 kJ/mol

H2O2 → ½ O2 + H2O      H= -95 kJ/mol

I am not sure what the answer to the second part is. I think that it is either -95 kJ/mol or -190 kJ/mol. I just want to make sure which one it is.

  • 2 weeks later...

It is  -190 kj/mol

Because

  1. 2H2 + O2  -> 2H2O   H= -572 kj/mol
  2. 2H2O2 -> 2H2 + 2O2   H= 382 kj/mol
  3. 2H2 + 2O2 + 2H2O -> 2H2O2 +2H2 + O2   H= 190 kj/mol
  4. 2H2O2 -> O2 + 2H2O    H= -190 kj/mol

-572+382+190-190= -190kj/mol

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