The ΔHf^∘ of TiI3(s) is -328 kJ / mol, and the ΔH^∘ for the reaction 2 Ti(s)+3 I2(g) ⟶2 TiI3(s)

step 1 So we have some data for the change in entropy of formation of T .I .I .3. This is negative 3 to

The ΔHf^∘ of TiI3(s) is -328 kJ / mol, and the ΔH^∘ for the...

The $\Delta H_{\mathrm{f}}^{\circ}$ of $\mathrm{TiI}_{3}(s)$ is $-328 \mathrm{kJ} / \mathrm{mol},$ and the $\Delta H^{\circ}$ for the reaction $2 \mathrm{Ti}(s)+3 \mathrm{I}_{2}(g)$ $\longrightarrow 2 \mathrm{TiI}_{3}(s)$ is $-839 \mathrm{kJ}$. Calculate the $\Delta H$ of sublimation (the state transition from solid to gas) of $\mathrm{I}_{2}(s),$ which is a solid at $25^{\circ} \mathrm{C}$ .

Key Concepts

Standard Enthalpy of Formation

The standard enthalpy of formation is the heat change that occurs when one mole of a compound is formed from its constituent elements in their standard states. This concept is essential for comparing the stabilities of different compounds and serves as a basis for calculating reaction enthalpies through various thermodynamic cycles.

Hess's Law

Hess's Law states that the total enthalpy change for a chemical reaction is independent of the pathway taken from reactants to products. This principle allows one to combine steps, such as formation reactions and phase changes, to determine an unknown enthalpy change by summing known enthalpy changes from intermediate reactions.

Sublimation Enthalpy

Sublimation enthalpy is the energy required to convert a substance from its solid phase to its gaseous phase directly, without an intermediate liquid phase. Understanding this concept is crucial when analyzing phase transitions, especially when a reaction involves a substance in a non-standard state due to phase changes.

Enthalpy Change for Phase Transitions

Enthalpy changes associated with phase transitions quantify the heat absorbed or released when a substance changes its state, such as during melting, vaporization, or sublimation. This concept is key in thermodynamics for describing how energy is involved in altering a substance's molecular interactions during a state change.

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