Complete Whole Notebook

Electrolytes and Nonelectrolytes- An electrolyte 7 is a compound that conducts an electric
current when it is an aqueous solution or in the molten core. Conduction of an electric current
requires ions that are mobile and, thus, able to carry charges through a liquid. All ionic compounds
are electrolytes because they dissociate into ions. Barium sulfate is an ionic compound that cannot
conduct an electric current in aqueous solution because it is insoluble, but it can conduct in the
molten core. A nonelectrolyte 8 is a compound that does not conduct an electric current in either an
aqueous solution or the molten state. Many molecular compounds are nonelectrolytes because they
are not composed of ions. Most compounds of carbon, such as table sugar and the alcohol in rubbing
alcohol, are nonelectrolytes. In a solution that contains a strong electrolyte 9 , all or nearly all of the
solute exists as ions. The ions move in solution and conduct an electric current. Most soluble salts,
inorganic acids, and inorganic bases are strong electrolytes. A weak electrolyte 10 conducts an
electric current poorly because only a fraction of the solute in the solution exists as ions. Organic
acids and bases are also examples of weak electrolytes.
Hydrates- The water contained in a crystal is called the water of hydration 11 or water of
crystallization. A compound that contains water of hydration is called a hydrate 12 . A substance that is
anhydrous 13 does not contain water. If a hydrate has a pressure higher than the pressure of water
vapor in the air, the hydrate will lose its water of hydration or effloresce 14 . These hydrates and other
compounds that remove moisture from air called hygroscopic 15 . A desiccant 16 is a substance used to
absorb moisture from the air and create a dry atmosphere. These compounds are deliquescent 17 ,
which means that they remove sufficient water from air to dissolve completely and form solutions.
The forces holding the water molecules in hydrates are not very strong, so the water is easily lost and
regained.
15.3 Heterogeneous Aqueous Systems
Suspensions- In contrast, heterogeneous mixtures are not solutions. A suspension 18 is a mixture
from which particles settle out upon standing. A suspension differs from a solution because the
particles of a suspension are much larger and do not stay suspended indefinitely. Suspensions are
heterogeneous because at least two substances can be clearly identified.
Colloids- A colloid 19 is a heterogeneous mixture containing particles that range in size from 1 nm to
1000nm. The particles are spread, or dispersed, throughout the dispersion medium, which can be
solid, liquid, or gas. The scattering of visible light by colloidal particles is called the Tyndall effect 20 .
The chaotic movement of colloidal particles, which was first observed by the Scottish botanist Robert
Brown (1773-1858), is called Brownian motion 21 . An emulsion 22 is a colloidal dispersion of a liquid in
a liquid. Colloids have particles smaller than those in suspensions and larger than lose in solutions.
Many colloids are cloudy or milky in appearance, like suspensions, when they are concentrated.
Colloids may look clear or almost clear, like solutions, when they are diluted. The important difference
between colloids and solutions and suspensions is in the size of the particles. The first substances to
be identified as a colloid was glue. Other substances that were also colloids were paint, aerosol
spray, and smoke.
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