Chemistry Homework: Calculate Enthelpy Change

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SUMMARY

The discussion focuses on calculating the enthalpy change for the combustion of methane (CH4) using bond dissociation energies. The equation used is enthalpy = D(reactants) - D(products), where D represents bond dissociation energies. The calculated enthalpy change for the reaction CH4 + 2O2 ---> 2H2O + CO2 is -668 kJ, derived from the provided bond dissociation energy values. The calculation involves summing the bond energies of the reactants and subtracting the bond energies of the products.

PREREQUISITES
  • Understanding of thermodynamics and enthalpy concepts
  • Familiarity with bond dissociation energies
  • Knowledge of chemical reaction equations
  • Basic algebra for calculations
NEXT STEPS
  • Study bond dissociation energies in detail for various compounds
  • Learn about Hess's Law and its application in enthalpy calculations
  • Explore the concept of standard enthalpy of formation
  • Investigate the role of enthalpy in exothermic and endothermic reactions
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Chemistry students, educators, and anyone involved in thermodynamics or chemical engineering who seeks to understand enthalpy changes in chemical reactions.

shawonna23
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1. Calculate the approximate enthalpy change for the combustion of methane:
CH4 + 2O2 ---> 2H20 + CO2

2. Homework Equations

CH4 + 2O2 ---> 2H20 + CO2

enthalpy= D(reactants) - D(products)

D= bond dissociation energies

Bond Dissociation energy (KJ/MOL)

C-C 350
C=C 611
C-H 410
C-O 350
C=O 732
O-O 180
O=O 498
H-O 460

3. The Attempt at a Solution

ENTHALPY= D(reactants)-D(products)
[1640+(2*498)]-[(2*920)-1464]= -668 kJ
 
Last edited:
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shawonna23 said:
[1640+(2*498)]-[(2*920)-1464]= -668 kJ

Why [(2*920)-1464]?

--
 

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