Con base en datos del apéndice C, calcule ΔG^∘ de las reacciones siguientes. Indique en cada cas

Con base en datos del apéndice C, calcule ΔG^∘ de las...

Con base en datos del apéndice $C$, calcule $\Delta G^{\circ}$ de las reacciones siguientes. Indique en cada caso si la reacción es espontánea en las condiciones estándar. (a) $2 \mathrm{SO}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{SO}_3(\mathrm{~g})$ (b) $\mathrm{NO}_2(g)+\mathrm{N}_2 \mathrm{O}(g) \longrightarrow 3 \mathrm{NO}(g)$ (c) $6 \mathrm{Cl}_2(\mathrm{~g})+2 \mathrm{Fe}_2 \mathrm{O}_3(\mathrm{~s}) \longrightarrow 4 \mathrm{FeCl}_3(\mathrm{~s})+3 \mathrm{O}_2(\mathrm{~g})$ (d) $\mathrm{SO}_2(\mathrm{~g})+2 \mathrm{H}_2(\mathrm{~g}) \longrightarrow \mathrm{S}(\mathrm{s})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{g})$

Con base en datos del apéndice $C$, calcule $\Delta G^{\circ}$ de las reacciones siguientes. Indique en cada caso si la reacción es espontánea en las condiciones estándar.
(a) $2 \mathrm{SO}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{SO}_3(\mathrm{~g})$
(b) $\mathrm{NO}_2(g)+\mathrm{N}_2 \mathrm{O}(g) \longrightarrow 3 \mathrm{NO}(g)$
(c) $6 \mathrm{Cl}_2(\mathrm{~g})+2 \mathrm{Fe}_2 \mathrm{O}_3(\mathrm{~s}) \longrightarrow 4 \mathrm{FeCl}_3(\mathrm{~s})+3 \mathrm{O}_2(\mathrm{~g})$
(d) $\mathrm{SO}_2(\mathrm{~g})+2 \mathrm{H}_2(\mathrm{~g}) \longrightarrow \mathrm{S}(\mathrm{s})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{g})$

Key Concepts

Reaction Spontaneity

Reaction spontaneity under standard conditions is determined by the sign of the calculated ?G°. If ?G° is negative, the reaction is spontaneous and can occur without the need for external energy; if it is positive, the reaction is non-spontaneous under standard conditions and would require an input of energy to proceed.

Standard Conditions

Standard conditions for thermodynamic calculations typically include a pressure of 1 atm for gases and a temperature of 298 K, along with specified concentrations for solutes. These conditions provide a common basis for comparing the energetics of different reactions.

Standard Gibbs Free Energy of Reaction

This concept refers to the overall change in Gibbs free energy (?G°) that occurs when a reaction proceeds under standard conditions. It is calculated by taking the difference between the sum of the Gibbs free energies of formation of the products (each multiplied by its stoichiometric coefficient) and that of the reactants. A negative ?G° indicates that the reaction is spontaneous under standard conditions, while a positive value denotes non-spontaneity.

Standard Free Energies of Formation

Standard free energies of formation (?G°f) are tabulated values representing the change in Gibbs free energy when one mole of a compound is formed from its elements in their standard states. These values are essential for calculating the ?G° of a reaction and are used in the equation ?G°_reaction = ?(?G°f products) – ?(?G°f reactants).

Transcript

00:01 We are asked to perform delta g calculations for four reactions and to indicate whether these reactions are spontaneous or not under standard conditions.

00:15 Equation number one.

00:24 We're using appendix c data and there's equation number one.

00:41 So delta g to solve for our free energy, that will equal our products, values that we look up.

00:55 Minus the sum of the delta gs for the products, some of the delta gs for the reactants.

01:00 Ground states are zero.

01:05 So i'm just going to indicate our zeros, where we have zeros, this one is zero.

01:13 So2 is negative 300 .4.

01:18 This one is negative 370 .4.

01:23 So our calculation will be as follows.

01:29 2 times negative 370 .4, and that'll be in kilojoules, minus 2 times 300 .4.

01:51 I'm going to leave these out of the calculations and just put them in at the end.

01:57 This will equal negative 1, 40 .0 kilojoules.