Consider the decomposition of gaseous N2 O4: N2 O4(g) ⟶2 NO2(g) ΔH^∘=+55.3 kJ ; ΔS^∘=+175.7 J

step 1 All right, so we're looking at the decomposition of a mole of dinitrogen tetroxide into two mole

Consider the decomposition of gaseous N2 O4: N2 O4(g) ⟶2...

Consider the decomposition of gaseous $\mathrm{N}_{2} \mathrm{O}_{4}$: $$\mathrm{N}_{2} \mathrm{O}_{4}(g) \longrightarrow 2 \mathrm{NO}_{2}(g) \quad \Delta H^{\circ}=+55.3 \mathrm{kJ} ; \Delta S^{\circ}=+175.7 \mathrm{J} / \mathrm{K}$$ (a) Is this reaction spontaneous under standard-state conditions at $25^{\circ} \mathrm{C} ?$ (b) Estimate the temperature at which the reaction becomes spontaneous.

Consider the decomposition of gaseous $\mathrm{N}_{2} \mathrm{O}_{4}$:
$$\mathrm{N}_{2} \mathrm{O}_{4}(g) \longrightarrow 2 \mathrm{NO}_{2}(g) \quad \Delta H^{\circ}=+55.3 \mathrm{kJ} ; \Delta S^{\circ}=+175.7 \mathrm{J} / \mathrm{K}$$
(a) Is this reaction spontaneous under standard-state conditions at $25^{\circ} \mathrm{C} ?$
(b) Estimate the temperature at which the reaction becomes spontaneous.

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Key Concepts

Gibbs Free Energy

Gibbs free energy is a thermodynamic potential that combines enthalpy and entropy to predict whether a process or reaction will occur spontaneously under constant temperature and pressure. It is given by the equation ?G = ?H – T?S, where a negative ?G indicates a spontaneous reaction, while a positive ?G implies non-spontaneity.

Enthalpy

Enthalpy is a measure of the heat content of a system at constant pressure. It represents the energy change due to the breaking and formation of bonds in a chemical reaction. An endothermic reaction, characterized by a positive enthalpy change, absorbs energy from the surroundings.

Entropy

Entropy is a measure of the disorder or randomness in a system. In chemical reactions, an increase in entropy (positive ?S) indicates a higher degree of molecular disorder, which can favor the spontaneity of a reaction according to thermodynamic principles.

Temperature Dependence of Reaction Spontaneity

Reaction spontaneity is highly dependent on temperature because the T?S term in the Gibbs free energy equation can overcome a positive enthalpy change at higher temperatures. At a particular temperature where ?G equals zero, the reaction is at the threshold of spontaneity. This temperature can be estimated by setting ?H equal to T?S.

Transcript

Please give Ace some feedback