Consider the decomposition of calcium carbonate: $$ \mathrm{CaCO}_{3}(s) \rightleftharpoons \mathrm{CaO}(s)+\mathrm{CO}_{2}(g) $$ Calculate the pressure in atm of \(\mathrm{CO}_{2}\) in an equilibrium process (a) at \(25^{\circ} \mathrm{C}\) and \((\mathrm{b})\) at \(800^{\circ} \mathrm{C}\). Assume that \(\Delta H^{\circ}=177.8 \mathrm{~kJ} / \mathrm{mol}\) and \(\Delta S^{\circ}=160.5 \mathrm{~J} / \mathrm{K} \cdot \mathrm{mol}\) for the temperature range.

Short Answer

Expert verified
The pressure of \(\mathrm{CO}_{2}\) at \(25^{\circ} \mathrm{C}\) and \(800^{\circ} \mathrm{C}\) can be obtained by utilizing the Van't Hoff equation and the ideal gas law based on the given \( \Delta H^{\circ} \) and \( \Delta S^{\circ} \) values. Solve for K then substitute it into \( P = K \) for each temperature to obtain the respective pressures.

Step by step solution

01

Calculation at \(25^{\circ} \mathrm{C}\)

First, convert the temperature from Celcius to Kelvin. Thus, \(T = 25 + 273.15 = 298.15 \, K\). Then, use the Van't Hoff equation \( \ln K = -\frac{\Delta H}{R} \times \frac{1}{T} + \frac{\Delta S}{R}\) to solve for K, where R is the gas constant with a value of \(0.008314 \, \mathrm{kJ} \cdot \mathrm{K}^{-1} \cdot \mathrm{mol}^{-1}\). This will yield \( K = e^{-\frac{177.8}{0.008314 \times 298.15} + \frac{160.5}{0.008314}} \).
02

Calculation of Pressure at \(25^{\circ} \mathrm{C}\)

Solving for the equilibrium constant K from Step 1, substitute this value into the expression for pressure in an ideal gas, \( P = K \). Thus, the pressure at \(25^{\circ} \mathrm{C}\) can be obtained.
03

Calculation at \(800^{\circ} \mathrm{C}\)

Repeat Steps 1 and 2 at \(800^{\circ} \mathrm{C}\). Thus, \(T = 800 + 273.15 = 1073.15 \, K\). Then, compute for the equilibrium constant K, and subsequently the pressure in the similar manner as Steps 1 and 2.

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