posted by John .
1.What is the molar heat of vaporization of water, given the following thermochemical equations?
H2 + 1/2 O2 --> H2O + 241.8 kJ
H2 + 1/2 O2 --> H2O + 285.5 kJ
a) 44.0 kJ/mol
2. Which substance has a standard enthalpy of formation delta Hf, equal to zero?
b)water ( liquid state)
I can't seem to get the correct answer...
Isn't the answer to #1 just the difference between the liquid and the gas (which you didn't label)? And since we are talking vaporization, that must be +.
For #2, elements are defined as having Hf = zero; therefore, both Au and Zn qualify.