Phase Change Chemistry Example 2

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Example 2

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Why does the temperature remain constant during a phase change, even though heat is being added?

Solution

  1. 1
    During a phase change, the added heat energy is used to overcome intermolecular forces (break bonds between molecules).
  2. 2
    The energy goes into changing the arrangement of particles, not increasing their kinetic energy.
  3. 3
    Since temperature is a measure of average kinetic energy, the temperature stays constant until the phase change is complete.

Answer

Energy overcomes intermolecular forces instead of increasing kinetic energy.\text{Energy overcomes intermolecular forces instead of increasing kinetic energy.}
This is why a heating curve shows flat plateaus at the melting point and boiling point. The energy absorbed at these points is called the heat of fusion or heat of vaporization.

About Phase Change

A physical transition from one state of matter to another caused by adding or removing thermal energy, during which the temperature remains constant as energy.

Learn more about Phase Change →

More Phase Change Examples

Example 1 easy

Name the six phase changes and indicate whether each absorbs or releases energy.

Example 3 easy

What phase change occurs when dry ice ([formula]) goes directly from solid to gas?

Example 4 hard

A heating curve shows a substance warming from [formula] to [formula]. It has a melting point of [fo

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