Name: _______________________
Date: ________________________
Flynt - ___Period
___th Grade Science
A solution is a mixture of one substance dissolved in another so the properties are the same throughout. A
solution is composed of a solute and the solvent. The solute is the substance being dissolved and the
solvent is the part of the solution that does the dissolving. The solute is of molecular size.
Examples of Solutions:
Gas
Liquid
Solid
Gas
Oxygen and other
gases in nitrogen
(air)
Liquid
Carbon dioxide in
water (carbonated
water)
Ethanol (common alcohol) in
water; various hydrocarbons in
each other (petroleum) *
Sucrose (table sugar) in
water; sodium chloride
(table salt) in water
Solid
Hydrogen
dissolved to
palladium
Water in activated charcoal
Steel, Brass, other metal
alloys
Water vapor in air (humidity)
The odor of a solid -molecules of that solid
being dissolved in the air
* Two liquids that are soluble are said to be miscible in one another.
Strength of Solutions
The solubility is the amount of solute that be dissolved in a given amount of solvent at any one
temperature. A solution is said to be unsaturated as long as more solute can be dissolved.
Dilute or Weak Solution - only a small amount of solute compared to solvent.
Concentrated Solution - A relatively large amount of solute to solvent.
Saturated Solution --At this point, the concentration of the solute in solution is the maximum possible
under the existing conditions (temperature and pressure). A solution is saturated when no more solute
can be dissolved at the current temperature. A saturated solution is one in which the dissolved and
undissolved solutes are in equilibrium.
Supersaturated Solution -- a solution that contains more dissolved substance than does a saturated
solution; the solution is not in equilibrium with the pure substance.
An example of a supersaturated solution is carbonated water, which is a supersaturated solution of
carbon dioxide gas in water. At the elevated pressure inside a Coca-Cola bottle, more carbon dioxide can
dissolve in water than would dissolve at atmospheric pressure. If exposed to atmospheric pressure, the
carbon dioxide gas would escape very slowly from the supersaturated liquid; this is why your Coke goes
flat over time. However, the escape process may be accelerated by the presence of nucleation sites within
the solution, such as small bubbles, which may be caused by shaking the bottle, or adding another solute,
such as sugar powder. A Diet Coke and Mentos eruption is a rather extreme example.
Other examples: Super-saturated solutions of sugar and water are commonly used to make rock
candy. Scuba divers' tissues become saturated with breathing gases during a dive. If the diver ascends
too fast, these gases form bubbles, resulting in decompression sickness.
Water is the Universal Solvent
Although water is sometimes called the universal solvent, there are many things it cannot dissolve. For
example water and oil do not mix. We say oil is immiscible in water.
What makes water such a good solvent?
Water is a good solvent due to its polarity. The solvent properties of water are vital in biology, because
many biochemical reactions take place only within aqueous solutions
When an ionic or polar compound enters water, it is surrounded by water molecules. The relatively
small size of water molecules typically allows many water molecules to surround one molecule of solute.
The partially negative dipoles of the water are attracted to positively charged components of the solute,
and vice versa for the positive dipoles.
Assessment Questions: Multiple Choice Questions
1. In a solution the substance that does the dissolving is called ___
a) soluble
b) the solute
c) the solvent
d) an ion
2. Water is a good solvent because
a) Water is a good solvent because it is a negatively charged ion.
b) Water is such a good solvent because it repels most molecules
c) Water is such a good solvent because it is such a small molecule
d) Water is a good solvent due to its polarity and small molecular size
3. A solution that cannot hold any more solute at room temperature would be ___
a) a dilute solution
b) a concentrated solution
c) a saturated solution
d) a supersaturated solution
4. Ethanol dissolved in water would be an example of ___
a) a solution between two miscible liquids
b) a solution between a solid and liquid
c) a suspension between two liquids
d) ethanol and water do not form a solution
5. To form a supersaturated solution requires
a) reducing the amount of solute
b) increasing the amount of solute in a solution
c) increasing the temperature of a saturated solution so more solute can be added
d) none of the above