Is the Conversion of NO2 to HNO3 endo- or exothemic?
Calculate the enthalpy and free energy change for the reaction
4NO2 + o2 + 2H2O-----> 4HNO3
in the aqueous phase.
To determine if the conversion of NO2 to HNO3 is endothermic or exothermic, we need to consider the enthalpy change (ΔH) for the reaction. If ΔH is positive, the reaction is endothermic, while if ΔH is negative, the reaction is exothermic.
To calculate the enthalpy change for the reaction, we can use the following steps:
Step 1: Determine the enthalpy change for the formation of HNO3
HNO3 is the product of the reaction, so we'll need to look up the enthalpy of formation (ΔHf) for HNO3. Let's assume it is -207 kJ/mol.
Step 2: Determine the enthalpy change for the formation of NO2
NO2 is one of the reactants, and we'll need its enthalpy of formation, which is around +34 kJ/mol.
Step 3: Calculate the overall enthalpy change for the reaction
Since there are 4 moles of NO2 being converted to 4 moles of HNO3, we need to multiply the enthalpy change for the formation of HNO3 by 4. On the other hand, since there are 4 moles of NO2, we'll need to multiply the enthalpy change for the formation of NO2 by 4 as well.
ΔH = (4 × ΔHf of HNO3) - (4 × ΔHf of NO2)
ΔH = (4 × -207 kJ/mol) - (4 × 34 kJ/mol)
Now you can calculate the value of ΔH.
To calculate the free energy change (ΔG) for the reaction, we need to use the equation:
ΔG = ΔH - TΔS
Where T is the temperature in Kelvin, and ΔS is the change in entropy.
To calculate ΔS, we require information about the change in entropy for the reaction. Unfortunately, the information provided does not include the values for ΔS. Therefore, it is not possible to calculate the free energy change (ΔG) without the value of ΔS.
In summary, to determine if the conversion of NO2 to HNO3 is endothermic or exothermic, you need to calculate the enthalpy change (ΔH) using the steps described above. However, without the value of ΔS, it is not possible to calculate the free energy change (ΔG) for the reaction.
Look up delta H formation and use
dHrxn = (n*dHf products) - (n*dHf reactants).
Do the same for dGo.