How to Calculate Delta H for Chemical Reactions Using Given Data and Equations?

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SUMMARY

The discussion focuses on calculating the enthalpy change (Delta H) for the reaction 2N2 + 5O2 -> 2N2O5 using Hess's Law. Participants provide relevant equations and their corresponding Delta H values: H2 + 1/2O2 -> H2O (Delta H = -285.5 kJ), N2O5 + H2O -> 2HNO3 (Delta H = -76.5 kJ), and 1/2N2 + 3/2O2 + 1/2H2 -> HNO3 (Delta H = -170.3 kJ). The key takeaway is the necessity to rearrange and combine these equations to derive the Delta H for the target reaction.

PREREQUISITES
  • Understanding of Hess's Law
  • Familiarity with enthalpy changes in chemical reactions
  • Knowledge of thermochemical equations
  • Ability to manipulate and combine chemical equations
NEXT STEPS
  • Study Hess's Law in detail to understand its application in thermodynamics
  • Learn how to manipulate thermochemical equations for enthalpy calculations
  • Explore examples of Delta H calculations for various chemical reactions
  • Investigate the significance of standard enthalpy of formation values
USEFUL FOR

Chemistry students, chemical engineers, and professionals involved in thermodynamics and reaction energetics will benefit from this discussion.

bard
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calculate delta h of this eq
2N2 + 5o2 -> 2N2O5
giventhis data
h2 + 1/2o2 -> h20
and delta h of that is -285.5
n2o5 + h2o -> 2nho3 delta h -76.5
and
1/2n2 + 3/2 o2 + 1/2h2 -> hno3 delta h -170.3
 
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Are you familiar with Hess's Law? Rearrange the bottom 3 equations by modifying them and combining them to make it look like the unknown.
 
bard, you have to show what you know and have tried, before we can help you.
 

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