We are taking a closer look at what happens when hot water is cooled down or ice is heating up (0:30).

After a brief review of the terminology of phase changes (1:11) we are taking a closer look at the particles in solid, liquids and gases (1:29). Focusing on the energy component of phase changes, we are describing the five segments of a heating curve (2:22). In segments where the temperature increases with increasing heat added, we are increasing the particle motion and can calculate the heat added using mCΔT (3:26). In segments where the temperature is not increased, the energy added is used to overcome the intermolecular forces. For these segments we use the enthalpies of fusion and vaporization to calculate the heat added (5:54). The episode closes with three important reminders about the heat of vaporization, the magnitude of enthalpies for a cooling curve and a reminder about the units for the calculations (6:26).

Question: Which of the following substances would have the greatest enthalpy of fusion?

A. methane (CH4) B. acetic acid (CH3COOH) C. ethanol (C2H5OH)

Thank you for listening to The APsolute RecAP: Chemistry Edition!

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