to calculate the energy released during the hydrogenation of prop-1-ene to propane.

Question

ScanSolve AI Tutor · Accepted Answer

The question asks to calculate the energy released during the hydrogenation of prop-1-ene to propane.

First, write the balanced chemical equation for the reaction:

\text{CH}_2=\text{CH}-\text{CH}_3 + \text{H}_2 \longrightarrow \text{CH}_3-\text{CH}_2-\text{CH}_3

Next, identify the bonds broken and bonds formed during the reaction.

Bonds broken:

Bonds formed:

One $\text{C}-\text{C}$ bond (the double bond becomes a single bond).
Two $\text{C}-\text{H}$ bonds (one on each carbon that was part of the double bond).

From the table:

Calculate the total energy required to break bonds.
$\text{Energy (broken)} = \text{Bond energy}(\text{C}=\text{C}) + \text{Bond energy}(\text{H}-\text{H})$ $\text{Energy (broken)} = 611 \text{ kJ/mol} + 435 \text{ kJ/mol}$ $\text{Energy (broken)} = 1046 \text{ kJ/mol}$
Calculate the total energy released when new bonds are formed.
$\text{Energy (formed)} = \text{Bond energy}(\text{C}-\text{C}) + 2 \times \text{Bond energy}(\text{C}-\text{H})$ $\text{Energy (formed)} = 346 \text{ kJ/mol} + 2 \times 413 \text{ kJ/mol}$ $\text{Energy (formed)} = 346 \text{ kJ/mol} + 826 \text{ kJ/mol}$ $\text{Energy (formed)} = 1172 \text{ kJ/mol}$
Calculate the overall energy change (enthalpy of reaction).
The energy released during the reaction is the difference between the energy released from forming bonds and the energy absorbed for breaking bonds.
$\Delta H = \text{Energy (broken)} - \text{Energy (formed)}$ $\Delta H = 1046 \text{ kJ/mol} - 1172 \text{ kJ/mol}$ $\Delta H = -126 \text{ kJ/mol}$
The negative sign indicates that energy is released.

The energy released during the hydrogenation of prop-1-ene to propane is $\boxed{\text{126 kJ/mol}}$ .

To calculate the energy released during the hydrogenation of prop-1-ene to propane.