Nitrogen dioxide, NO2(g), is an emission resulting from the burning of gasoline in the air in an automobile engine. nitrogen dioxide contributes to the formation of smog and acid rain. it can be converted to dinitrogen tetraoxide as shown below:
2NO2(g) --> N2O4(g)
a) use Hess's law and the following equations to determine the enthalpy change for this reaction.
1) N2(g) +2O2(g) --> 2NO2(g) ΔH^o = 66.4 k/J
2) N2(g) + 2O2(g) --> N2O4(g) ΔH^o = 11.1 k/j
b) write the thermochemical equation for the overall reaction.
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I think you reposted this same question and two people solved this question and got the answer, here is the link:
www.jiskha.com/questions/1802849/Nitrogen-dioxide-NO2-g-is-an-emission-resulting-from-the-burning-of-gasoline-in
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a) To determine the enthalpy change for the reaction, we can use 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 in the reaction pathway.
We are given two equations:
1) N2 (g) + 2O2 (g) → 2NO2 (g) ΔH° = 66.4 kJ
2) N2 (g) + 2O2 (g) → N2O4 (g) ΔH° = 11.1 kJ
Let's assume we want to find the enthalpy change for the conversion of 2NO2 (g) to N2O4 (g). We can manipulate the given equations to cancel out the common species (N2 and O2) and sum up the enthalpy changes.
First, we flip equation 1) to reverse the direction of the reaction, so it becomes:
2NO2 (g) → N2 (g) + 2O2 (g) ΔH° = -66.4 kJ
Next, we sum equation 1) and the reversed equation of 2):
2NO2 (g) + 2NO2 (g) → N2 (g) + 2O2 (g) + N2O4 (g)
By canceling out the common species (N2 and O2), we obtain the overall equation:
4NO2 (g) → 2N2O4 (g) ΔH° = -66.4 kJ + 11.1 kJ = -55.3 kJ
Therefore, the enthalpy change for the reaction 2NO2 (g) → N2O4 (g) is -55.3 kJ.
b) The thermochemical equation for the overall reaction can be written as:
4NO2 (g) → 2N2O4 (g) ΔH° = -55.3 kJ
This equation represents the conversion of four molecules of nitrogen dioxide to two molecules of dinitrogen tetraoxide with an enthalpy change of -55.3 kJ.