Enthalpy of Formation

by Physics197
Tags: enthalpy, formation
Physics197 is offline
Jan23-10, 03:11 PM
P: 74
1. The problem statement, all variables and given/known data

Using the enthalpies of formation given below, calculate ΔHrxn in kJ, for the following reaction.

3NO2(g)+1H2O(l) -> 2HNO3(g)+1NO(g)

NO2 (g): 33.10 kJ/mol
H2O (l): -285.83 kJ/mol
HNO3 (l): -174.10 kJ/mol
NO (g): 90.29 kJ/mol

2. Relevant equations

dHrxn = dHproducts - dHreactants

3. The attempt at a solution

Is this possible to do since the equation says HNO3 is a gas, but they give the enthalpy of formation for HNO3 as a liquid.
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physstudent1 is offline
Jan26-10, 09:03 PM
P: 271
its possible but you need to use another enthalpy term that accounts for the latent heat which is from the phase transfer of liquid to gas
chemisttree is offline
Jan27-10, 03:24 PM
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That would be the Hvap of HNO3.

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