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 CO_{2} at 410°C using standard thermodynamic data for the given balanced reaction:
PbCO_{3} (s) ⇌ PbO(s) + CO_{2} (g)
Recall that the equilibrium constant is the ratio of the products and reactants. We use K_{p} 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:
$\overline{){\mathbf{\Delta G}}{{\mathbf{\xb0}}}_{{\mathbf{rxn}}}{\mathbf{=}}{\mathbf{-}}{\mathbf{RTlnK}}}$
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) |
PbCO_{3} (s) | –699.1 | 131.0 |
PbO(s) | –217.3 | 68.7 |
CO_{2} (g) | –393.5 | 213.8 |
We can use the following equation to solve for ΔG˚_{rxn}:
$\overline{){\mathbf{\Delta G}}{{\mathbf{\xb0}}}_{{\mathbf{rxn}}}{\mathbf{=}}{\mathbf{\Delta H}}{{\mathbf{\xb0}}}_{{\mathbf{rxn}}}{\mathbf{-}}{\mathbf{T\Delta S}}{{\mathbf{\xb0}}}_{{\mathbf{rxn}}}}$
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 (K_{p}).
Step 5 : From K_{p}, solve for equilibrium partial pressure of CO_{2}
Problem Details
Using data in Appendix C in the textbook, calculate the equilibrium pressure of CO_{2} in the system at 410 ^{o}C.
Frequently Asked Questions
What scientific concept do you need to know in order to solve this problem?
Our tutors have indicated that to solve this problem you will need to apply the Gibbs Free Energy concept. You can view video lessons to learn Gibbs Free Energy Or if you need more Gibbs Free Energy practice, you can also practice Gibbs Free Energy practice problems .
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Based on our data, we think this problem is relevant for Professor Stoltzfus' class at OSU.