The molar heats of formation of liquid and gas phase water are given by: kJ H₂ (9) + 02 (9) → H₂O(l) ΔΗ, = -285.8 mol H₂ (g) + O₂ (9) → H₂O (g) Use these equations and values of AHF to determine the amount of heat transferred in the process of evaporating 1 mole of liquid water under constant pressure. H₂O(l) → H₂O (9) AHƒ = ? AH = -241.8 kJ mol
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
![The molar heats of formation of liquid and gas phase water are given by:
\[ \textbf{H}_2 (g) + \frac{1}{2} \textbf{O}_2 (g) \rightarrow \textbf{H}_2\textbf{O} (\ell) \quad \Delta H_f = -285.8 \, \frac{\text{kJ}}{\text{mol}} \]
\[ \textbf{H}_2 (g) + \frac{1}{2} \textbf{O}_2 (g) \rightarrow \textbf{H}_2\textbf{O} (g) \quad \Delta H_f = -241.8 \, \frac{\text{kJ}}{\text{mol}} \]
Use these equations and values of \( \Delta H_f \) to determine the amount of heat transferred in the process of evaporating 1 mole of liquid water under constant pressure.
\[ \textbf{H}_2\textbf{O} (\ell) \rightarrow \textbf{H}_2\textbf{O} (g) \quad \Delta H_f = ? \]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F9ca9b71c-5031-49ba-83a5-105a41edc8d4%2F207d9b64-cd28-4692-94fd-80cb4274903c%2F4jhhkd9_processed.jpeg&w=3840&q=75)
The enthalpy change is a state function and the Hess law states that the change of enthalpy in a chemical reaction is independent of the pathway between the initial and final states.
According to this law, the total enthalpy change during a complete chemical reaction is the same whether the reaction is made in one step or in several steps.
Step by step
Solved in 3 steps with 4 images
