The heating curve for a substance is shown below. The substance initially is a solid. It then becomes a liquid and a gas. Which of the line segments (I-V) represents the solid to liquid phase transition?

Question

Quizplus · Accepted Answer

Line segment II represents the solid to liquid phase transition because the substance is absorbing heat during this period while maintaining a constant temperature. This is because the energy is being used to break the intermolecular bonds between the particles in the solid, allowing them to move more freely and become a liquid. After this transition, the substance will continue to absorb heat and increase in temperature until it reaches its boiling point and undergoes a phase transition from liquid to gas (represented by line segment IV).

The Heating Curve for a Substance Is Shown Below