Humboldt State University ® Department of Chemistry

Richard A. Paselk

Chem 109 - General Chemistry - Spring 2013

Lecture Notes 33: 24 April

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Liquids & Solids, cont.

Heating & Cooling Curves

A consideration of vapor pressure etc leads to the behaviors of substances with increasing (or decreasing) temperature (see Fig 10.44, p 476 of Zumdahl 8th ed):

plot of heating curve for water

Solutions —General Information

Solutions: a solution occurs when one chemical is completely dissolved or dispersed in another. We most commonly think of solutions as being liquid, but solid solutions also occur, such as the various metal alloys like steel, brass and bronze.

In a solution the substance present in highest concentration is considered to be the solvent, while components in lesser amounts are considered to be solutes. If you dissolve a sugar cube in water you get a sugar solution, where water is the solvent, and sugar is the solute.

FYI

Example:

  • What is the solvent in 80 proof rum: 80 proof = 40% alcohol in water, so water is the solvent.
  • What is the solvent in 151 proof rum: 151 proof = 75.5% alcohol in water, so alcohol is the solvent.

 Solubility

All gases are completely soluble in each other.

Liquid solutions

"Like dissolves like."

Solids and Crystals

Solids:Recall earlier definition - solids have fixed or definite shapes and volumes. By this definition solids are strictly limited to the crystalline solids. (The amorphous (noncrystalline) solids discussed in our text are what we have discussed as supercooled liquids.)

 

Crystal (Solid) Structure

Crystal Structure (overheads)

Types of Solids

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© R A Paselk

Last modified 24 Apr 2013