Chemistry

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Which of the following substances have a standard heat of formation (ÄHf°) of zero?

O2(g) at 25.0 degree C and 1 atm
Fe at 1200 degree C
C2H6(g) at standard conitions
Cl2(g) at 2 atm

  • Chemistry -

    O2 @ 25 C and 1 atm is the only one.
    Fe yes but at 25 C, not 1200.
    C2H6 no since it's a compound.
    Cl2 yes at 25 C and 1 atm but not at 2 atm.

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