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Ch.19 - Chemical Thermodynamics

Chapter 19, Problem 111d

The reaction SO2(g) + 2 H2S(g) ⇌ 3 S(s) + 2 H2O(g) is the basis of a suggested method for removal of SO2 from power-plant stack gases. The standard free energy of each substance is given in Appendix C. (d) Would you expect the process to be more or less effective at higher temperatures?

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Hello. Everyone in this video, we're trying to see if the reaction given over here becomes more or less effective as the temperature rises. We can find this information out by solving for our change of entropy is our delta H. Or change in entropy which is our delta S. So we're given all the values that we can use to go ahead and sell for these. So first let's go ahead and solve our delta H. So our delta H. Of the reaction is the delta age of our products minus the delta H. Of our reactant. So again we're just using the values given to us right over here in this table. So first we're being asked for the death of age of our products and we know that our products are on the right side. So we just need to match these up with this. We do that, we see that for our delta H. Of our products. Let's see here. So we have one more multiplied with zero killer jewels promote and then we're gonna go ahead and add one more Multiplied by. Let's see here we have a value of -241.82 killer joules per mole. So we see here that for our carbon here we have zero value and we have one mole of um the carbon for water, we have the delta H. Value of negative 2 41. So that's how I got this. So we're going to continue the same method for our reactant. So again we have one more multiplied by negative 110.5 units being killed jules Permal subtracting this with one mole mortified by zero killer jewels per mole. So once I put all this into my calculator I can get that my delta H. Of this reaction is equal to negative 131. killer jewels per month. Now for my delta S. The the reaction or the equation to solve for delta S. Exactly miss this except for H values will put us. So tell to us is equal to the entropy or the entropy of our reactant. So discovery. So the entropy of our products minus the entropy of a reactant. Again using the table of values given to us right over here You can see that we're dealing with this here, one mole multiplied by 5.69 jewels per mole times Calvin. And then we're adding that with let's see one mall times 188.83. Again, units being jules Permal times kelvin. And then we're gonna go ahead and subtract this with one more Times 197. Jewels Per Mole Times Kelvin. And then we're gonna go ahead and add, let's see the next reactant would be we have one more of that and then we're looking at the entropy value that's going to be 130.58 jewels per mole times kelvin. So once we put that all into our calculator, we see that the change of entropy is going to be equal to negative 133.96 jewels per kelvin. Okay, so we see here that from what we saw for their delta H value is negative. Are delta S value is also negative. So when we have both values being negative, this reaction will only be spontaneous at lower temperatures. So of course as the temperature rises, then the reaction will be less effective. Let's go ahead, write that answer out. So we can say that the reaction will be less effective as the temperature prices. Alright, so this is going to be my final answer for this problem. Thank you all so much for watching.
Related Practice
Textbook Question

Consider the following equilibrium: N2O4(g) ⇌ 2 NO2(g) Thermodynamic data on these gases are given in Appendix C. You may assume that ΔH° and ΔS° do not vary with temperature. (a) At what temperature will an equilibrium mixture contain equal amounts of the two gases?

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Textbook Question

The reaction SO2(g) + 2 H2S(g) ⇌ 3 S(s) + 2 H2O(g) is the basis of a suggested method for removal of SO2 from power-plant stack gases. The standard free energy of each substance is given in Appendix C. (b) In principle, is this reaction a feasible method of removing SO2?

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Textbook Question

The reaction SO2(g) + 2 H2S(g) ⇌ 3 S(s) + 2 H2O(g) is the basis of a suggested method for removal of SO2 from power-plant stack gases. The standard free energy of each substance is given in Appendix C. (c) If PSO2 = PH2S and the vapor pressure of water is 25 torr, calculate the equilibrium SO2 pressure in the system at 298 K.

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Textbook Question

When most elastomeric polymers (e.g., a rubber band) are stretched, the molecules become more ordered, as illustrated here:

Suppose you stretch a rubber band. (a) Do you expect the entropy of the system to increase or decrease?

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Textbook Question
Hydrogen gas has the potential for use as a clean fuel in reaction with oxygen. The relevant reaction is 2 H21g2 + O21g2 ¡ 2 H2O1l2 Consider two possible ways of utilizing this reaction as an electrical energy source: (i) Hydrogen and oxygen gases are combusted and used to drive a generator, much as coal is currently used in the electric power industry; (ii) hydrogen and oxygen gases are used to generate electricity directly by using fuel cells that operate at 85 °C. (a) Use data in Appendix C to calculate ∆H° and ∆S° for the reaction. We will assume that these values do not change appreciably with temperature.
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