Considere la reacción siguiente: PbCO3( s) ⇌PbO(s)+CO2( g) Con base en datos del apéndice C, cal

Considere la reacción siguiente: PbCO3( s) ⇌PbO(s)+CO2( g)...

Considere la reacción siguiente: $$ \mathrm{PbCO}_3(\mathrm{~s}) \rightleftharpoons \mathrm{PbO}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g}) $$ Con base en datos del apéndice $C$, calcule la presión de equilibrio de $\mathrm{CO}_2$ en el sistema a (a) $120^{\circ} \mathrm{C}$ y (b) $480^{\circ} \mathrm{C}$.

Considere la reacción siguiente:
$$
\mathrm{PbCO}_3(\mathrm{~s}) \rightleftharpoons \mathrm{PbO}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})
$$

Con base en datos del apéndice $C$, calcule la presión de equilibrio de $\mathrm{CO}_2$ en el sistema a (a) $120^{\circ} \mathrm{C}$ y (b) $480^{\circ} \mathrm{C}$.

Key Concepts

Chemical Equilibrium

This is the state in which the rates of the forward and reverse reactions are equal, leading to constant concentrations (or partial pressures) of all species involved. It is fundamental to understanding how reactions can reach a balanced state and how various factors influence this balance.

Heterogeneous Equilibrium

Heterogeneous equilibrium refers to a chemical equilibrium involving more than one phase (solid, liquid, gas). In these cases, only the species in the gas or aqueous phase appear in the equilibrium constant expression, while pure solids or liquids are omitted because their activities are constant.

Equilibrium Constant (Kp) for Gaseous Reactions

For reactions involving gases, the equilibrium constant (Kp) is defined in terms of the partial pressures of the gaseous components. In reactions where solids are present along with gases, Kp depends solely on the partial pressures of the gaseous species, simplifying the calculation of equilibrium pressure from thermodynamic data.

Temperature Dependence of Equilibrium

The value of the equilibrium constant is temperature-dependent, a relationship often explored through the van ’t Hoff equation or linked to changes in the Gibbs free energy. Understanding this dependence is crucial for predicting how the equilibrium position will shift with temperature changes, which in turn affects the pressure or concentration of the species involved.

Transcript

00:01 Consider the reaction given here between lead to carbonate, not between, of lead to carbonate decomposing into lead to oxide and carbon dioxide gas in the reversible reaction.

00:14 We're asked to lose data, use data from appendix c and calculate the equilibrium pressure of co2 first at 400 degrees.

00:24 Okay, so let's see.

00:26 So we can find out all of our standard values from appendix c.

00:30 We can get our delta gs, our s's, and our delta h values, and we're going to do some calculations.

00:46 So step one.

00:47 First, we're going to find our delta h for the reaction and delta s.

01:13 Okay, which i have to find here, and the delta g.

01:28 Okay, so let's do delta s.

01:30 I don't know, let's do delta h first.

01:39 And don't forget that all of our, all will be like sum of products minus thumb of reactants.

01:56 And then i'm going to move this down a little bit, so i have room to write.

02:03 And that will equal.

02:08 So i'll write the substance up here, pbo, and that will be, i'm going to leave my units off for brevity.

02:23 And then we'll subtract from that one times my that'll be 699 .1.

02:57 This is my pb, co3.

03:02 This is my co2.

03:05 This is this.

03:07 These are units of kilojoules per mole.

03:11 This is small for all of these.

03:15 So our delta h will be equal to 88 .3 kilojoules.

03:22 I'm squeakly underlined under that.

03:30 And then my delta s will be, i'm going to make note, all my coefficients are one.

03:41 So this will be one times 68 .70 plus one times 213 .6.

03:58 Plus, excuse me, minus 1 times 130, oops, 131 .0.

04:11 Now this one will be in joules per kelvin, joules per k -mole, i should say.

04:23 Jules per k -mole, and of course, these are moles.

04:36 My delta s will be equal to 151 .3 joules per kmole.

04:46 Kelvin.

04:50 And then let's do our delta g, which will be one times 88 .3.

05:08 Wait, maybe i won't do that one.

05:21 Hmm.

05:26 What am i going to do? equilibrium pressure.

05:30 Okay...

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