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Ch.19 - Chemical Thermodynamics
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All textbooksBrown 14th EditionCh.19 - Chemical ThermodynamicsProblem 88e

Chapter 19, Problem 88e

For each of the following processes, indicate whether the signs of ΔS and ΔH are expected to be positive, negative, or about zero. (e) A piece of charcoal is combusted to form CO2(g) and H2O(g).

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Hello everyone. So in this video we're trying to predict the science for our DELTA S. And DELTA H. For the decomposition of calcium carbonate. So we're going to talk about the meaning behind a different sense of the DELTA X. And DELTA H. And relate that and look at the reaction and kind of apply it so I can think about this as a key then. So if we have a negative DELTA H. This means that bonds are forming and if we have a phase change it would be from gas face to liquid or liquid to solid or gas to solid. Now if we have a positive DELTA H. This means that bonds are going to be breaking in the reaction. And if there is a phase change, the puzzle changes is basically opposite of r minus R negative delta H. Going from solid to liquid to gas or solid to gas or liquid to gas. All right now talking about the change in entropy. So if our DELTA S. Is greater than zero, basically if we have a positive DELTA S then this means our entropy is increasing. Now if we have a delta S that is less than zero, basically we have a negative DELTA S. Then the entropy is decreasing. Alright, so let's go ahead and compose our reaction first because we're only given the starting materials and products. Let's formally our chemical reaction. So of course we have our starting material being calcium carbonate. So C. A. C. 03. That's a solid and that's going to go ahead decomposed into C. AO which is a solid given to us the problem and C. 02 a gas. So we can see here from this reaction, then that bonds are definitely breaking. So if bonds are breaking, we said that it will be a positive delta um H. And as for our delta S, let's take a look here. So we're starting off with one mole of solid. Then we're forming one mole of solid and one mole of gas. So basically going from one mole of substance into two moles of substance. So we're increasing our entropy. Therefore, we have a positive delta S. And these two here are going to be the signs of the decomposition of calcium carbonate. Thank you all so much for watching.
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