Final Notebook

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. Some polar molecule
compounds are nonelectrolytes in the pure state but become electrolytes when they dissolve in water.
A ​strong electrolyte​ 9​ ​is where all of the solute exists as ions. Most soluble salts, inorganic acids and
inorganic bases are examples of a strong electrolyte. A ​weak electrolyte​ 10​ conducts an electric current
poorly because only a fraction of the solute exist as ions. Organic acids and bases are also examples
of weak electrolytes. Electrolytes are important because our body uses electrolytes such as sodium
and potassium ions. These create electrical impulses which are crucial to muscle function.
Electrolytes can be found in sports drinks and salty foods.
Hydrates
The water contained in a crystal is called the ​water of hydration​ 11​ ​or water crystallization. A ​Hydrate​12
is what a compound that contains water of hydration is called. The forces holding the water molecules
in hydrates are not very strong, so the water is easily lost and regained. A substance that is
anhydrous​ 13​ ​does not contain water. Water molecules in hydrates are held by weak forces so
hydrates often have an appreciable vapor pressure. If a hydrate has a vapor pressure higher than the
pressure of water vapor in the air, the hydrate will lose its water of hydration or ​effloresce​14​.
Hygroscopic​ 15​ hydrates are compounds that remove moisture to form higher hydrates. A ​desiccant​ 16
is a substance used to absorb moisture from the air and create a dry atmosphere. When a desiccant
has absorbed all the water it can hold, the compound can be returned to its anhydrous state by
heating. Some compounds are so hygroscopic that they become wet when exposed to normally moist
air.​ Deliquescent​ 17​ compounds remove sufficient water from the air to dissolve completely and form
solutions. The solution formed by a deliquescent substance has a lower vapor pressure than that of
the water in the air.
15.3 Heterogeneous Aqueous Systems
Suspensions
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 1nm to 1000nm.
Particles are spread or dispersed , throughout the dispersion medium, which can be solid, liquid, or
gas.Types of colloids are glue, mixing paint, aerosol sprays and smoke.The important difference
between colloids, solutions and suspensions is in the size of the particles. Colloids have particles
smaller than those in suspensions and larger than those in solutions. They are a subject to a
phenomenon called Tyndall effect and by the observation of Brownian motion. They are also a
subject to coagulation or clumping together and they can be emulsified or made stable. The ​Tyndall
effect​20​ is the scattering of visible light by colloidal particles. Suspensions also exhibit the Tyndall
effect but solutions do not. The ​Brownian motion​ 21​ is caused by collisions of the molecules of the
dispersion medium with the small dispersed colloidal particles from settling. Colloidal particles also
tend to stay suspended because they become charged by absorbing ions from the dispersing
medium onto their surface. All the colloidal particles in a particular colloidal system will have the same
charge, although the colloidal system is neutral. An ​emulsion​ 22​ is a colloidal dispersion of a liquid in a
liquid. For example, oils and greases are not soluble in water. Soaps and other emulsifying agents
thus allow the formation of colloidal dispersion between liquids that do not ordinarily mix.
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