- #1

winterwind

- 29

- 0

## Homework Statement

Calculate [tex]\Delta[/tex]

_{r}H

^{0}and [tex]\Delta[/tex]

_{r}U

^{0}at 348 K for the hydrogenation of ethyne (acetylene) to ethene (ethylene) from the enthalpy of combustion and heat capacity data in Tables 2.5 and 2.7. Assume the heat capacaties to be constant over the temperature range involved.

[tex]\Delta[/tex]

_{f}H

^{0}of ethyne = +226.73 kJ/mol

[tex]\Delta[/tex]

_{p,m}C

^{0}of ethyne = 43.93

[tex]\Delta[/tex]

_{f}H

^{0}of ethene = +52.26 kJ/mol

[tex]\Delta[/tex]

_{p,m}C

^{0}of ethene = 43.56

Other relevant data in the tables are also given, such as Enthalpy of fusion, enthaply of combustion, molar heat capacity, Benson thermochemical groups, of various molecules, including water, oxidation, hydrogen gas, carbon dioxide gas, ethane, ethene, and ethyne.

I only included the above because I think I would need to use those for sure. The other data can be easily found.

## Homework Equations

Hess's Law

Kirchhoff's Law

## The Attempt at a Solution

I might try combining equations to arrive at the right equation (Hess's Law). Maybe Kirchoff's Law to find the values at 348 K? What is meant by [tex]\Delta[/tex]

_{r}U

^{0}? Is this the change in internal energy? How does it relate to enthalpy (fusion, heat capacity, etc.)?

Thanks!

EDIT: I only need help with question in post #2 now. I figured out the other parts already.

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