Calculate Enthalpy Change of N2 + O2 Reaction

[jalen]

Calculate the enthalpy change of the following reaction between nitrogen gas and oxygen gas, given thermochemical equations (1),(2),and(3).
(1) 2H_2(g) + O_2(g) ---> 2H₂O_(l) H=-572KJ
(2) N₂O_{5 (g)} + H₂O_(l) --->2HNO_{3 (l)} H=-77KJ
(3)1/2 N_{2 (g)} + 3/2 O_{2 (g)} +1/2 H_{2 (g)} ---> HNO_{3 (l)} H=-174KJ

 

[Kushal]

write equation of the reaction of nitrogen with oxygen. what is the product?

notice that nitrogen and oxygen are both elements in their standard conditions. the product will be N2O5 only, so the equation is the enthalpy change of formation of N2O5.

you only have to rearrange the above 3 eqns to obtain the enthalpy of formation of N2O5.

 

[Blueshift5]

To calculate the enthalpy change of the reaction between nitrogen gas (N2) and oxygen gas (O2), we need to first determine the overall reaction equation. Based on the given thermochemical equations, we can combine equations (1) and (3) to obtain the desired reaction:

2H2(g) + O2(g) ---> 2H2O(l) H=-572KJ
1/2 N2 (g) + 3/2 O2 (g) +1/2 H2 (g) ---> HNO3 (l) H=-174KJ

Combining these two equations, we get:

N2(g) + O2(g) + H2(g) ---> 2HNO3(l) H=-746KJ

Now, to calculate the enthalpy change of this reaction, we need to use the Hess's Law, which states that the total enthalpy change of a reaction is equal to the sum of the enthalpy changes of the individual steps involved in the reaction.

Therefore, the enthalpy change of the reaction between N2 and O2 can be calculated as follows:

ΔH = ΣΔH(products) - ΣΔH(reactants)
= [2(-77KJ) + 1(-174KJ)] - [1(-746KJ)]
= -328KJ

Therefore, the enthalpy change of the reaction between N2 and O2 is -328KJ. This indicates that the reaction is exothermic, as the enthalpy change is negative.