Determine H for N2 + O2 -> 2NO with Given Information

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Discussion Overview

The discussion revolves around calculating the enthalpy change (ΔH) for the reaction N2 + O2 -> 2NO using given thermodynamic data and Hess's Law. Participants explore the application of Hess's Law to derive the ΔH for the specified reaction, while also addressing a related reaction involving iron oxides and carbon monoxide.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant presents a series of reactions and their associated enthalpy changes to derive ΔH for the reaction N2 + O2 -> 2NO, suggesting a final value of 178.27 kJ.
  • The same participant questions the units for ΔH, assuming they are in kJ despite the lack of explicit mention.
  • Another participant references a previous thread that discusses a general method for solving Hess's Law problems, indicating that there are established approaches to tackle such calculations.
  • A later reply expresses agreement with the calculations presented, stating that they arrive at the same numbers for both problems discussed.

Areas of Agreement / Disagreement

There is no explicit consensus on the final value of ΔH for the reaction N2 + O2 -> 2NO, as the calculations presented are based on assumptions and interpretations of the data. Some participants express agreement with the calculations, but the overall discussion remains unresolved regarding the exact value and methodology.

Contextual Notes

The discussion includes various assumptions about the reactions and their enthalpy changes, and there may be dependencies on the definitions of the reactions used. The calculations involve multiple steps that are not fully detailed, leaving some mathematical aspects unresolved.

Who May Find This Useful

Students and enthusiasts interested in thermodynamics, particularly those studying Hess's Law and enthalpy calculations in chemical reactions.

Soaring Crane
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Given the following information:
Fe2O3 + 3CO -> 2Fe + 3CO2 Heat = -28.0 kJ
3Fe + 4CO2 -> 4 CO + Fe3O4 Heat =-12.5 kJ
FInd the heat for the following reaction:
Fe2O3 + CO -> CO2 + Fe3O4
Balance the equation first and remember to include the correct units.

3Fe2O3 + CO -> CO2 + 2Fe3O4

Fe2O3 + 3CO --> 2Fe + 3CO2 H = -28 kJ
2(3Fe + 4CO2 --> 4CO + Fe3O4 H = -12.5 kJ)

3(Fe2O3 + 3CO --> 2Fe + 3CO2 H = -28.0 kJ)
6Fe + 8CO2 --> + 2 Fe3O4 H = -25.0 kJ

3Fe2O3 + 9CO --> 6Fe + 9CO2 H = -84.0
6Fe + 8CO2 --> 8CO + 2Fe3O4 H = -25.0 kJ

Thus, 3Fe2O3 + CO -> CO2 + 2Fe3O4 and H = -109 kJ??


Use the presented information to find the  H for: N2 + O2 ->2NO
1/2 N2 + O2 -> NO2 H = 32.16
4NO + 2O2 ->4NO2 H = -227.9

1/2 N2 + O2 -> NO2 H = 32.16
1/2 (4NO + 2O2 ->4NO2 H = -227.9)

2(1/2 N2 + O2 -> NO2 H = 32.16)
2NO2 --> 2NO + O2 H = +113.95

N2 + 2O2 --> 2NO2 H = 64.32
2NO2 --> 2NO + O2 H = +113.95

Thus, N2 + O2 ->2NO and H = 178.27 = 178.3 ?? I suppose the units are kJ even if they didn't state which units are used?

Thanks.
 
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Any volunteers?

Thanks again.
 
Soaring Crane said:
Any volunteers?

Thanks again.
I get the same numbers on both problems. You're doing good.
 

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