Which one has the higher enthelpy, the reactent or the product?

  • Thread starter Thread starter Lion214
  • Start date Start date
  • Tags Tags
    Product
Click For Summary
SUMMARY

The discussion centers on the enthalpy comparison between 2Cl(g) and Cl2(g) in the reaction 2Cl(g) → Cl2(g) with a ΔH of -243.4 kJ. It is established that 2Cl(g) possesses a higher enthalpy than Cl2(g) under the specified conditions. The confusion arises from the misconception that reversing the reaction would yield the same enthalpy change in magnitude but opposite in sign. The key takeaway is that the enthalpy change reflects the energy released during the exothermic reaction, indicating that the products (Cl2) have lower energy than the reactants (2Cl).

PREREQUISITES
  • Understanding of thermodynamics principles, particularly enthalpy.
  • Familiarity with exothermic and endothermic reactions.
  • Knowledge of chemical reaction equations and stoichiometry.
  • Basic grasp of the concept of energy changes in chemical reactions.
NEXT STEPS
  • Study the concept of enthalpy in detail, focusing on standard enthalpy changes.
  • Learn about Hess's Law and its application in calculating enthalpy changes.
  • Explore the differences between exothermic and endothermic reactions with specific examples.
  • Investigate the role of bond energies in determining the enthalpy of reactions.
USEFUL FOR

Chemistry students, educators, and professionals interested in thermodynamics and reaction energetics will benefit from this discussion.

Lion214
Messages
10
Reaction score
0
2Cl(g)→Cl2(g) ΔH = -243.4 KJ

Which has the higher enthalpy under these conditions, 2 Cl (g) or Cl2 (g)?





At first, I thought they would have the same change in enthalpy, because if I make it a reverse reaction, their magnitude will be the same. Then I realized that the signs would reverse, making the change of enthalpy for the product positive. Apparently that was not the answer, as 2 Cl(g) has a higher change in enthalpy. I'm posting this because I want to know why that is?
 
Physics news on Phys.org
Think in terms of the exo- and endothermic reaction. Where does the reaction heat come from?
 

Similar threads

Chemistry Does Combusting Different Amounts of Propane Change Final Temperature?
  • · Replies 5 ·
Replies
5
Views
3K
Chemistry Valence Bond Theory: Energy of a system with H and Cl atoms
  • · Replies 6 ·
Replies
6
Views
4K
Chemistry Understanding the calculation of enthalpy of the formation of benzene
  • · Replies 3 ·
Replies
3
Views
3K
Chemistry A calculation of enthalpy, entropy, and Gibbs energy of vaporization
  • · Replies 1 ·
Replies
1
Views
2K
Chemistry How do we use enthalpy of formation in this calculation?
  • · Replies 9 ·
Replies
9
Views
3K
Chemistry How to apply Nernst equation in this problem?
  • · Replies 3 ·
Replies
3
Views
3K
Enthalpy Question: H2 (g) + Cl2 (g) --> 2 HCl (g) + 184.62 kJ
  • · Replies 1 ·
Replies
1
Views
3K
Chemistry Why does a negative ΔH indicate an exothermic reaction?
  • · Replies 2 ·
Replies
2
Views
3K
Enthelpy of reaction calculation?
  • · Replies 6 ·
Replies
6
Views
14K
Chemistry Question about the Butler-Volmer equation in electrochemistry
  • · Replies 1 ·
Replies
1
Views
3K