Estimate the minimum temperature at which magnetite can be reduced to iron by graphite.
Fe₃O₄(s) + 2C(s) $\rightarrow$ 2CO₂(g) + 3Fe(s)
$\Delta$ S_r^$\circ$ = +351.44 J.K^-1.mol^-1
The standard molar enthalpies of formation of magnetite and CO₂(g) are -1118.4 and -393.51 kJ.mol^-1,respectively.

Question

Estimate the minimum temperature at which magnetite can be reduced to iron by graphite.
Fe₃O₄(s) + 2C(s)

\rightarrow

2CO₂(g) + 3Fe(s)

\Delta

S_r^$\circ$ = +351.44 J.K^-1.mol^-1
The standard molar enthalpies of formation of magnetite and CO₂(g) are -1118.4 and -393.51 kJ.mol^-1,respectively.

Quizplus · Accepted Answer

The standard molar entropy change for the reaction is positive, indicating that the reaction is entropy-driven. The standard molar enthalpy change for the reaction is negative, indicating that the reaction is exothermic. Therefore, the reaction is spontaneous at all temperatures. The minimum temperature at which the reaction can occur is the temperature at which the standard molar Gibbs free energy change for the reaction is zero. This temperature can be calculated using the equation:$\Delta$G$\circ$= $\Delta$H$\circ$- T$\Delta$S$\circ$where $\Delta$G$\circ$ is the standard molar Gibbs free energy change, $\Delta$H$\circ$ is the standard molar enthalpy change, T is the temperature in Kelvin, and $\Delta$S$\circ$ is the standard molar entropy change.Substituting the given values into the equation, we get:$\Delta$G$\circ$= -1118.4 kJ.mol$^-1$ - T(351.44 J.K$^-1$.mol$^-1$)Setting $\Delta$G$\circ$ to zero and solving for T, we get:T = 3182 KConverting to degrees Celsius, we get:T = 2909 $^o$CTherefore, the minimum temperature at which magnetite can be reduced to iron by graphite is 2909 $^o$C.

Estimate the Minimum Temperature at Which Magnetite Can Be Reduced →\rightarrow→

Estimate the Minimum Temperature at Which Magnetite Can Be Reduced $\rightarrow$