Considere la descomposición de benceno líquido, C6 H6(l), para dar acetileno gaseoso, C2 H2(g) :

step 1 All right. Hey, guys. Today we're doing problem 48 in chapter 5 of chemistry central science. So

Considere la descomposición de benceno líquido, C6 H6(l),...

Considere la descomposición de benceno líquido, $\mathrm{C}_6 \mathrm{H}_6(l)$, para dar acetileno gaseoso, $\mathrm{C}_2 \mathrm{H}_2(g)$ : $$ \frac{1}{3} \mathrm{C}_6 \mathrm{H}_6(l) \longrightarrow \mathrm{C}_2 \mathrm{H}_2(\mathrm{~g}) \quad \Delta H=+210 \mathrm{~kJ} $$ (a) Calcule el cambio de entalpía para la reacción inversa. (b) Determine $\Delta H$ para la descomposición de $1 \mathrm{~mol}$ de benceno a acetileno. (c) ¿Qué es más probable que se favorezca termodinámicamente, la reacción hacia adelante o la inversa? (d) $\mathrm{Si}$ se consumiera $\mathrm{C}_6 \mathrm{H}_6(\mathrm{~g})$ en lugar de $\mathrm{C}_6 \mathrm{H}_6(l)$, ¿cabría esperar que la magnitud de $\Delta H$ aumente, disminuya o permanezca igual? Explique.

Considere la descomposición de benceno líquido, $\mathrm{C}_6 \mathrm{H}_6(l)$, para dar acetileno gaseoso, $\mathrm{C}_2 \mathrm{H}_2(g)$ :
$$
\frac{1}{3} \mathrm{C}_6 \mathrm{H}_6(l) \longrightarrow \mathrm{C}_2 \mathrm{H}_2(\mathrm{~g}) \quad \Delta H=+210 \mathrm{~kJ}
$$
(a) Calcule el cambio de entalpía para la reacción inversa. (b) Determine $\Delta H$ para la descomposición de $1 \mathrm{~mol}$ de benceno a acetileno. (c) ¿Qué es más probable que se favorezca termodinámicamente, la reacción hacia adelante o la inversa? (d) $\mathrm{Si}$ se consumiera $\mathrm{C}_6 \mathrm{H}_6(\mathrm{~g})$ en lugar de $\mathrm{C}_6 \mathrm{H}_6(l)$, ¿cabría esperar que la magnitud de $\Delta H$ aumente, disminuya o permanezca igual? Explique.

Key Concepts

Effect of Physical State on Enthalpy

The physical state of a reactant or product, such as being in a liquid or gaseous phase, influences the enthalpy due to differences in intermolecular forces and the energy required to overcome them. Changes in phase can alter the energy change of a reaction, making it important to consider the specific state when comparing reaction energetics.

Thermodynamic Favorability

Determining which direction of a reaction is thermodynamically favored involves analyzing the energy changes associated with the process, typically through Gibbs free energy. In general, processes that release energy (exothermic reactions) tend to be more spontaneously favored under standard conditions, though entropy changes also play a role.

Stoichiometry and Scaling of Enthalpy

Enthalpy is an extensive property, meaning that its value depends on the amount of substance involved in the reaction. Applying the proper stoichiometric coefficients allows one to scale the enthalpy change for different quantities of reactants or products, ensuring the energy balance is correctly maintained across various reaction formulations.

Reaction Reversal and Enthalpy Change Sign

When a reaction is reversed, the sign of the enthalpy change is inverted while the magnitude remains unchanged. This concept is important to understand because it explains that an endothermic reaction in one direction becomes exothermic in the opposite direction, and vice versa.

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