Problem: The reaction SO2(g) + 2H2S(g) ⇌ 3S(s) + 2H2O(g) is the basis of a suggested method for removal of SO2 from power-plant gases. The standard free energy of each substance are ΔGf°S(s) = 0 kJ/mol ΔGf°H2O(g) = -228.57 kJ/mol ΔGf°SO2(g) = -300.4 kJ/molΔGf° H2S (g) = -33.01kJ/molWhat is the equilibrium constant for the reaction at 298K?In principle, is this reaction a feasible method of removing SO2?If Pressure of SO2 = Pressure of H2S and the vapor pressure of water is 26 torr, calculate the equilibrium SO 2 pressure in the system at 298 K.Would you expect the process to be more or less effective at higher temperatures?

FREE Expert Solution

We are given the following reaction:


SO2(g) + 2 H2S(g)  3 S(s) + 2 H2O(g)


We are asked to do the following:

  • Determine the equilibrium constant, k, for the reaction.
  • Calculate the equilibrium pressure of SO2(g) when Pressure of H2S = Pressure of SO2 and the vapor pressure of water is 26 torr.

Find the equilibrium constant, k.

Recall that ΔG˚rxn and K are related to each other:


ΔG°rxn=-RTlnK


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


ΔG°rxn=ΔG°f, prod-ΔG°f, react


In determining k, we need to do the following steps:

Step 1: Calculate for ΔG˚rxn.

Step 2: Calculate for K.


Step 1: Calculate for ΔG˚rxn:

Given:

ΔG˚f, SO2(g) = – 300.4 kJ/mol

ΔG˚f, H2S(g) = – 33.01 kJ/mol

ΔG˚f, S(s)     = 0 kJ/mol

ΔG˚f, H2O(g) = – 228.57 kJ/mol


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Problem Details

The reaction SO2(g) + 2H2S(g) ⇌ 3S(s) + 2H2O(g) is the basis of a suggested method for removal of SO2 from power-plant gases. The standard free energy of each substance are 

ΔGf°S(s) = 0 kJ/mol 

ΔGf°H2O(g) = -228.57 kJ/mol 

ΔGf°SO2(g) = -300.4 kJ/mol

ΔGf° H2S (g) = -33.01kJ/mol

What is the equilibrium constant for the reaction at 298K?
In principle, is this reaction a feasible method of removing SO2?
If Pressure of SO2 = Pressure of H2S and the vapor pressure of water is 26 torr, calculate the equilibrium SO 2 pressure in the system at 298 K.
Would you expect the process to be more or less effective at higher temperatures?

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