Reaction

Temperature

400

K

Reaction coordinate

0.00

Directions

Details

About

C_{2}H_{2} + H_{2} → C_{2}H_{4}

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This simulation calculates the heat of reaction at the temperature selected by the slider. The blue line is the enthalpy of the reactants, and the green line is the enthalpy of the products. The black arrowed line represents the heat of reaction at the temperature selected. Choose among three reactions using the drop-down menu labelled "Reaction". The governing equations are under Details.

The heat of reaction at a given temperature \( \Delta H^{ \circ }_{T} \) is calculated from the standard state heat of reaction \( \Delta H^{ \circ }_{298} \) and temperature-dependent heat capacity \( C_{p} \) of the mixture:

$$ \Delta H^{ \circ }_{T} = \Delta H^{ \circ }_{298} + \int_{298}^{T} \Delta C_{p} dT $$where

$$ \Delta C_{p} = \sum_{i}^{n} \nu_{i} C_{p, i} $$where \( \nu_{i} \) is the stoichiometric coefficient of component \( i \), \( C_{p, i} \) is the heat capacity of component \( i \), and \( n \) is the number of components in the reaction. Heat capacity data are fit using the Shomate equation:

$$ C_{p, i} = A + BT + CT^{2} + DT^{3} + \frac{ E }{ T^{2} } $$where \( A \), \( B \), \( C \), \( D \), and \( E \) are constants, and \( T \) is temperature in Kelvin. The resulting equation for heat of reaction \( \Delta H_{rxn} \) is therefore

$$ \Delta H^{ \circ }_{T} = \Delta H^{ \circ }_{298} + \sum_{i}^{n} \left[ \nu_{i} A_{i} (T - 298) + \frac{ \nu_{i} B_{i} }{ 2 } ( T^{2} - 298^{2} ) + \frac{ \nu_{i} C_{i} }{ 3 } ( T^{3} - 298^{3} ) + \frac{ \nu_{i} D_{i} }{ 4 } ( T^{4} - 298^{4} ) + \frac{ (T - 298) }{ 298 } \frac{ \nu_{i} E_{i} }{ T } \right] $$

This simulation was created in the Department of Chemical and Biological Engineering, at University of Colorado Boulder for LearnChemE.com by Neil Hendren under the direction of Professor John L. Falconer. This simulation was prepared with financial support from the National Science Foundation. Address any questions or comments to learncheme@gmail.com. All of our simulations are open source, and are available on our LearnChemE Github repository.

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