Problem: Consider the following reaction: PbCO3 (s) ⇌ PbO(s) + CO2 (g)Using data in Appendix C in the textbook, calculate the equilibrium pressure of CO2 in the system at 410 oC.

FREE Expert Solution

We’re asked to calculate the equilibrium pressure of CO2 at 410°C using standard thermodynamic data for the given balanced reaction:

PbCO3 (s) ⇌ PbO(s) + CO2 (g)

Recall that the equilibrium constant is the ratio of the products and reactants. We use Kp when dealing with pressure

$\overline{){{\mathbf{K}}}_{{\mathbf{p}}}{\mathbf{=}}\frac{{\mathbf{P}}_{\mathbf{products}}}{{\mathbf{P}}_{\mathbf{reactants}}}}$

Note that solid and liquid compounds are ignored in the equilibrium expression.

Also, recall that ΔG˚rxn and K are related to each other:

$\overline{){\mathbf{\Delta G}}{{\mathbf{°}}}_{{\mathbf{rxn}}}{\mathbf{=}}{\mathbf{-}}{\mathbf{RTlnK}}}$

The thermodynamic data ( ΔH˚f and ΔS˚) of each reactant and product can be found in textbooks/online:

 Substance ΔH˚f (kJ/mol) S˚ (J/mol • K) PbCO3 (s) –699.1 131.0 PbO(s) –217.3 68.7 CO2 (g) –393.5 213.8

We can use the following equation to solve for ΔG˚rxn:

$\overline{){\mathbf{\Delta G}}{{\mathbf{°}}}_{{\mathbf{rxn}}}{\mathbf{=}}{\mathbf{\Delta H}}{{\mathbf{°}}}_{{\mathbf{rxn}}}{\mathbf{-}}{\mathbf{T\Delta S}}{{\mathbf{°}}}_{{\mathbf{rxn}}}}$

For this problem we need to do these steps:

Step 1: Calculate ΔH˚rxn.

Step 2: Calculate ΔS˚rxn.

Step 3: Use ΔH˚rxn and ΔS˚rxn to calculate for ΔG˚rxn.

Step 4: Calculate for K (Kp).

Step 5: From Kp, solve for equilibrium partial pressure of CO2

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Problem Details
Consider the following reaction: PbCO3 (s) ⇌ PbO(s) + CO2 (g)

Using data in Appendix C in the textbook, calculate the equilibrium pressure of CO2 in the system at 410 oC.