Question

Estimate the change in free energy whenundergoes photooxidation.

Short answer

The change in free energy when P960 undergoes photo-oxidation is 140kJ/mol.

Step-by-step solution

Photooxidation

The rate of photosynthesis can occasionally be inhibited by strong light intensities because they oxidize the chlorophyll and this process is referred to as photo-oxidation.

Step 2: The change in free energy

From the figure of photosynthetic electron-transport system of purple bacteria, the change in redox potential is $\Delta {\epsilon }^{o\text{'}}=-1.5V$.

In this case, n of electrons is 1.

The change in free energy is calculated using the following equation:

$$\begin{gathered} {\mathrm{\Delta G}}^{\mathrm{o}\text{'}}=-{\mathrm{nF\Delta \epsilon }}^{\mathrm{o}\text{'}} \\ {\mathrm{\Delta G}}^{\mathrm{o}\text{'}}=(-1)\times 96 \\ \begin{array}{c}{\mathrm{\Delta G}}^{\mathrm{o}\backslash \mathrm{cent}}=(-1)\times (96,485\mathrm{C}/\mathrm{mol})\times (-1.5\mathrm{V})\\ =140000\mathrm{J}/\mathrm{mol}\\ =140\mathrm{kJ}/\mathrm{mol}\end{array} \end{gathered}$$

Hence, the change in free energy is 140kJ/mol.