Explore BrainMass

Sample calculation of bond energies and enthalpies

This content was STOLEN from BrainMass.com - View the original, and get the already-completed solution here!

You may wish to review the Laws of Thermochemistry and Endothermic and Exothermic Reactions before you begin. A table of single bond energies should be used as a help (available in most general chemistry text books).

Estimate the change in enthalpy, DH, for the following reaction:

H2(g) + Cl2(g) --> 2 HCl(g)

© BrainMass Inc. brainmass.com October 24, 2018, 5:28 pm ad1c9bdddf

Solution Preview

To work this problem, think of the reaction in terms of simple steps:

First, the reactant molecules, H2 and Cl2, break down into their atoms
H2(g) --> 2 H(g)
Cl2(g) --> 2 Cl(g)

2. Next, these atoms combine to form HCl molecules
2 H(g) + 2 Cl(g) --> 2 HCl(g) ...

See Also This Related BrainMass Solution

Thermodynamics: Enthalpy and Entropy

1. Given that a formation of a bond between two atoms is exothermic and accompanied by an entropy decrease, explain why all chemical compounds decompose into individual atoms if heated to a high enough temperature.

2. Is the dissolution of urea driven by enthalpy or entropy? How do you know this? Give one example of each of a process that is driven by enthalpy, and one that is driven by entropy.

View Full Posting Details