Use the data in Appendix 4 for the following. a. Calculate \(\Delta H^{\circ}\) and \(\Delta S^{\circ}\) for the reaction $$3 \mathrm{Fe}_{2} \mathrm{O}_{3}(s)+\mathrm{CO}(g) \longrightarrow 2 \mathrm{Fe}_{3} \mathrm{O}_{4}(s)+\mathrm{CO}_{2}(g)$$ that occurs in a blast furnace. b. Assume that \(\Delta H^{\circ}\) and \(\Delta S^{\circ}\) are independent of temperature. Calculate \(\Delta G^{\circ}\) at \(800 .{ }^{\circ} \mathrm{C}\) for this reaction.

Short Answer

Expert verified
The calculated values are \(\Delta H^{\circ} = 1114.74\,\text{kJ/mol}\), \(\Delta S^{\circ} = -291.3\,\text{J/mol K}\), and \(\Delta G^{\circ} = 1427.44\,\text{kJ/mol}\) at 800°C.

Step by step solution

01

Calculate \(\Delta H^{\circ}\)

To find the standard enthalpy change (\(\Delta H^{\circ}\)) for the reaction, we need to subtract the standard enthalpies of formation for the reactants from the standard enthalpies of formation for the products. Using the data from Appendix 4, we can write the equation for \(\Delta H^{\circ}\) as follows: $$\Delta H^{\circ} = \big(2 \times \Delta H^{\circ}_{3Fe_{2}O_{3}}\big) - \big(3 \times \Delta H^{\circ}_{Fe_{3}O_{4}} + \Delta H^{\circ}_{CO}\big)$$ Now, plug in the values for the standard enthalpies of formation for each compound: $$\Delta H^{\circ} = \big(2 \times (-1120.29\,\text{kJ/mol})\big) - \big(3 \times (-1118.44\,\text{kJ/mol}) + (-110.53\,\text{kJ/mol})\big)$$ Calculate the value of \(\Delta H^{\circ}\): $$\Delta H^{\circ} = (-2240.58\,\text{kJ/mol}) - (-3355.32\,\text{kJ/mol}) = 1114.74\,\text{kJ/mol}$$
02

Calculate \(\Delta S^{\circ}\)

To find the standard entropy change (\(\Delta S^{\circ}\)) for the reaction, we need to subtract the standard entropies for the reactants from the standard entropies for the products. Using the data from Appendix 4, we can write the equation for \(\Delta S^{\circ}\) as follows: $$\Delta S^{\circ} = \big(2 \times S^{\circ}_{3Fe_{2}O_{3}} + S^{\circ}_{CO_{2}}\big) - \big(3 \times S^{\circ}_{Fe_{3}O_{4}} + S^{\circ}_{CO}\big)$$ Now, plug in the values for the standard entropies for each compound: $$\Delta S^{\circ} = \big(2 \times (146.4\,\text{J/mol K}) + (213.8\,\text{J/mol K})\big) - \big(3 \times (200.0\,\text{J/mol K}) + (197.9\,\text{J/mol K})\big)$$ Calculate the value of \(\Delta S^{\circ}\): $$\Delta S^{\circ} = (506.6\,\text{J/mol K}) - (797.9\,\text{J/mol K}) = -291.3\,\text{J/mol K}$$
03

Calculate \(\Delta G^{\circ}\) at 800°C

Now that we have the values for \(\Delta H^{\circ}\) and \(\Delta S^{\circ}\), we can calculate the standard Gibbs free energy change (\(\Delta G^{\circ}\)) at 800°C using the following equation: $$\Delta G^{\circ} = \Delta H^{\circ} - T\Delta S^{\circ}$$ Convert the temperature from Celsius to Kelvin: $$T = 800 + 273.15 = 1073.15\,\text{K}$$ Plug in the values for \(\Delta H^{\circ}\), \(\Delta S^{\circ}\), and T: $$\Delta G^{\circ} = 1114.74\,\text{kJ/mol} - (1073.15\,\text{K} \times -0.2913\,\text{kJ/mol K}) = 1114.74\,\text{kJ/mol} + 312.7\,\text{kJ/mol}$$ Calculate the value of \(\Delta G^{\circ}\): $$\Delta G^{\circ} = 1427.44\,\text{kJ/mol}$$ The standard Gibbs free energy change, \(\Delta G^{\circ}\), for the reaction at 800°C is 1427.44 kJ/mol.

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Most popular questions from this chapter

The complex ion \(\mathrm{Fe}(\mathrm{CN})_{6}{ }^{3-}\) is paramagnetic with one unpaired electron. The complex ion \(\mathrm{Fe}(\mathrm{SCN})_{6}{ }^{3-}\) has five unpaired electrons. Where does \(\mathrm{SCN}^{-}\) lie in the spectrochemical series relative to \(\mathrm{CN}^{-}\) ?

Draw geometrical isomers of each of the following complex ions. a. \(\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{2}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\right]^{-}\) c. \(\left[\operatorname{Ir}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]\) b. \(\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{I}_{2}\right]^{2+}\) d. \(\left[\mathrm{Cr}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{2} \mathrm{I}_{2}\right]^{+}\)

Use standard reduction potentials to calculate \(\mathscr{E}^{\circ}, \Delta G^{\circ}\), and \(K\) (at \(298 \mathrm{~K}\) ) for the reaction that is used in production of gold: $$2 \mathrm{Au}(\mathrm{CN})_{2}^{-}(a q)+\mathrm{Zn}(s) \longrightarrow 2 \mathrm{Au}(s)+\mathrm{Zn}(\mathrm{CN})_{4}^{2-}(a q)$$ The relevant half-reactions are $$\begin{aligned}\mathrm{Au}(\mathrm{CN})_{2}^{-}+\mathrm{e}^{-} \longrightarrow \mathrm{Au}+2 \mathrm{CN}^{-} & \mathscr{C}^{\circ} &=-0.60 \mathrm{~V} \\ \mathrm{Zn}(\mathrm{CN})_{4}^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Zn}+4 \mathrm{CN}^{-} & \mathscr{E}^{\circ} &=-1.26 \mathrm{~V} \end{aligned}$$

Consider the following data: $$\begin{aligned} \mathrm{Co}^{3+}+\mathrm{e}^{-} \longrightarrow \mathrm{Co}^{2+} & & \mathscr{E}^{\circ}=1.82 \mathrm{~V} \\ \mathrm{Co}^{2+}+3 \mathrm{en} \longrightarrow \mathrm{Co}(\mathrm{en})_{3}^{2+} & K &=1.5 \times 10^{12} \\ \mathrm{Co}^{3+}+3 \mathrm{en} \longrightarrow \mathrm{Co}(\mathrm{en}){ }^{3+} & K &=2.0 \times 10^{47} \end{aligned}$$ where en \(=\) ethylenediamine. a. Calculate \(\mathscr{E}^{\circ}\) for the half-reaction $$\mathrm{Co}(\mathrm{en})_{3}^{3+}+\mathrm{e}^{-} \longrightarrow \mathrm{Co}(\mathrm{en})_{3}^{2+}$$ b. Based on your answer to part a, which is the stronger oxidizing agent, \(\mathrm{Co}^{3+}\) or \(\mathrm{Co}(\mathrm{en})_{3}{ }^{3+}\) ? c. Use the crystal field model to rationalize the result in part b.

Sketch a \(d\) -orbital energy diagram for the following. a. a linear complex with ligands on the \(x\) axis b. a linear complex with ligands on the \(y\) axis

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