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Thermochemistry - Reaction between phosphorous and oxygen

  1. Nov 9, 2003 #1
    i come across this fact.

    red and white phosphorus are allotropes, but the reaction between white phosphorus with oxygen gives out slightly more heat than the reaction btw red phosphorus and oxygen.

    P4 (s) [red] + 5O2 (g) --> 2P2O5 (s)

    delta H = -30.2kJmol-1

    P4 (s) [white]+ 5O2 (g) --> 2P2O5 (s)

    delta H = -29.5kJmol-1

    from the equation given, it show that the reaction btw red phosphorus and oxygen liberate more heat.

    so, which one is correct?
  2. jcsd
  3. Nov 9, 2003 #2


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    Both. Ask yourself "What is the difference in enthalpies of formation of the allotropes?"
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