Question

10 what determines whether a phase change is endothermic or exothermic? a the initial pressure conditions of the environment b the color change of the substance undergoing the phase change c the time it takes for the phase change to complete d whether energy is absorbed or released during the change

Explanation:

• Endothermic phase changes involve the absorption of energy. For example, melting (solid to liquid) and vaporization (liquid to gas) require energy input.
• Exothermic phase changes involve the release of energy. For instance, freezing (liquid to solid) and condensation (gas to liquid) release energy.
• Pressure (Option A) affects the phase (e.g., boiling point changes with pressure), but not whether the phase change is endo - or exo - thermic.
• Color change (Option B) is a physical property change that is not related to heat absorption or release in determining endo/exothermic nature.
• Time to complete (Option C) is a kinetic factor (related to rate) and not related to whether heat is absorbed or released.

Answer:

D. Whether energy is absorbed or released during the change