From the enthalpy of formation for CO2 and the following...

From the enthalpy of formation for $\mathrm{CO}_{2}$ and the following information, calculate the standard enthalpy of formation for carbon monoxide (CO). $$\mathrm{CO}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g) \quad \Delta H^{\circ}=-283.0 \mathrm{kJ} / \mathrm{mol}$$ Why can't we obtain the standard enthalpy of formation directly by measuring the enthalpy of the following reaction? $$\text { C(graphite) }+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)$$

From the enthalpy of formation for $\mathrm{CO}_{2}$ and the following information, calculate the standard enthalpy of formation for carbon monoxide (CO).
$$\mathrm{CO}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g) \quad \Delta H^{\circ}=-283.0 \mathrm{kJ} / \mathrm{mol}$$
Why can't we obtain the standard enthalpy of formation directly by measuring the enthalpy of the following reaction?
$$\text { C(graphite) }+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)$$

Key Concepts

Standard Enthalpy of Formation

This concept refers to the enthalpy change when one mole of a compound is formed from its elements in their standard states under standard conditions (usually 1 atm pressure and a specified temperature, typically 298 K). It is a fundamental thermodynamic quantity that serves as a basis for calculating the enthalpy changes of various reactions and for constructing energy cycles.

Hess's Law

Hess's Law states that the total enthalpy change for a reaction is the same, regardless of the pathway taken, as enthalpy is a state function. This principle enables the determination of reaction enthalpies by combining multiple steps with known enthalpy changes. It is particularly useful when the direct measurement of the enthalpy change for a given reaction is challenging.

Experimental Limitations in Measuring Reaction Enthalpies

Certain reactions are difficult to measure directly due to experimental challenges such as rapid kinetics, side reactions, and difficulties in controlling reaction conditions. In the case of forming CO from its elements, issues arise because the reaction may not proceed cleanly or may involve competing processes that lead directly to the more stable product, CO2. These factors make it impractical to obtain accurate direct measurements of the enthalpy change for the formation of CO.

Transcript

Please give Ace some feedback