Several processes are given in the table and labeled as endo- thermic or exothermic and given a sign for ∆H°. Which process is labeled with the correct sign of ∆H° and correct classification as endothermic or exothermic? (LO 9.8) Process (b) Methane, the main component of natural gas, is burned to produce a flame on a stovetop.

Verified step by step guidance

1. Identify the type of process: Burning methane is a combustion reaction.
2. Recall that combustion reactions are typically exothermic, meaning they release heat.
3. Understand that for exothermic reactions, the change in enthalpy (\( \Delta H^\circ \)) is negative because energy is released to the surroundings.
4. Consider the context: Methane combustion produces heat and light, consistent with an exothermic process.
5. Conclude that the correct classification for the process of burning methane is exothermic with a negative \( \Delta H^\circ \).

Key Concepts

Endothermic and Exothermic Reactions

Endothermic reactions absorb heat from their surroundings, resulting in a positive change in enthalpy (∆H° > 0). In contrast, exothermic reactions release heat, leading to a negative change in enthalpy (∆H° < 0). Understanding these classifications is crucial for determining the energy changes associated with chemical processes.

Enthalpy Change (∆H°)

Enthalpy change (∆H°) is a measure of the heat content of a system at constant pressure. It indicates whether a reaction is endothermic or exothermic based on the heat absorbed or released during the process. A negative ∆H° signifies an exothermic reaction, while a positive ∆H° indicates an endothermic reaction.

Combustion of Methane

The combustion of methane (CH₄) is an exothermic reaction where methane reacts with oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O), releasing energy in the form of heat and light. This process is commonly used in heating and cooking, exemplifying an exothermic reaction with a negative ∆H°.