Cracking the SAT Subject Test in Chemistry, 1 by Princeton Review

Author:Princeton Review
Language: eng
Format: epub
Publisher: Random House Children's Books
Published: 2018-02-13T05:00:00+00:00

More volatile liquid: • liquid that has higher vapor pressure

• evaporates more readily when temperature is below boiling point (compared to a less volatile liquid)

Less volatile liquid: • liquid that has lower vapor pressure

• evaporates less readily when temperature is below boiling point

ENERGY AND PHASE CHANGES

As we saw from the phase change diagram, a substance must absorb heat to change from a solid to a liquid to a gas. It must lose heat to turn from gas to liquid to solid. Heat, as you remember, is a form of energy. So, when you think of phases and energy, remember that among the three phases, solid is lowest in potential energy and gas is highest in potential energy.

One more thing: When ice melts, there is an increase in entropy, and when liquids vaporize, entropy increases even more. Under certain conditions, the increase in entropy (which the universe likes) is enough to overcome the increase in energy (which it dislikes) and make a phase change spontaneous. What are these conditions? Well, in the case of melting, if the substance is at a temperature above the melting point, the phase change will be spontaneous. In order for boiling to be spontaneous, the substance must be at a temperature above the boiling point.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.