Unit 5 Lesson 1 Solutions
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Unit 5 Lesson 1 Solutions
Mix It Up
What is a solution?
• A solution is a homogeneous mixture in which
two or more substances are so completely
blended and evenly distributed that you cannot
identify the different parts.
• A solution may be solid, liquid, or gas. Light
passes through gas and liquid solutions, so you
can see through them.
• Particles in solutions are so small that they cannot
be trapped and separated by a filter.
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Unit 5 Lesson 1 Solutions
What is a solution?
• Not all mixtures are solutions. A colloid contains
medium-sized particles that are distributed in a
gas, liquid, or solid. The particles are large
enough to scatter light passing through the
mixture but small enough not to settle or be
separated by a filter.
• In a suspension, large particles are distributed in
a gas or liquid. The particles do not dissolve, so
they block light and the mixture appears cloudy.
Particles eventually settle out of a suspension, or
they can be separated out by a filter.
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Unit 5 Lesson 1 Solutions
What is a solution?
• Which image shows a colloid, which a solution,
and which a suspension?
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Unit 5 Lesson 1 Solutions
What are the two parts of a solution?
• Solutions have two parts: the solute and the
solvent.
• The solute is the substance that is being
dissolved in a solution. A solute can be a liquid,
gas, or solid.
• The solvent is the substance in the solution that
does the dissolving. A solvent can also be a liquid,
gas, or solid. Water is the most common liquid
solvent.
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Unit 5 Lesson 1 Solutions
What are the two parts of a solution?
• As a solution forms, solute particles become
evenly distributed in the solvent. A homogeneous
mixture is formed.
• After a solution forms, it is not possible to visibly
distinguish between the solute and the solvent.
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Unit 5 Lesson 1 Solutions
Concentrate!
How can the concentration of a solution
vary?
• The measure of the amount of solute dissolved in
a solvent is called concentration.
• One way to calculate the concentration of a
solution is to divide the mass of the solute by the
volume of the solvent.
• The units of concentration are often expressed as
grams per milliliter (g/ml).
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Unit 5 Lesson 1 Solutions
How can the concentration of a solution
vary?
• A dilute solution contains a small amount of solute
in a given volume of solvent.
• A concentrated solution contains a large amount
of solute in a given volume of solvent.
• A saturated solution contains the most solute that
can be completely dissolved in a given amount of
a solvent at a given temperature and pressure. If
more solute is added to a container of a saturated
solution, it will settle to the bottom without
dissolving.
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Unit 5 Lesson 1 Solutions
How can the concentration of a solution
vary?
• Raising the temperature of a saturated solution
often allows more solute to dissolve. If the
solution is cooled very slowly, the extra solute
might stay dissolved. This type of solution is said
to be supersaturated.
• A supersaturated solution is very unstable. If even
a single crystal of solute is added, all the extra
solute will quickly solidify, so that it is no longer
dissolved in the solution. The result is often the
formation of beautiful crystals of the solute.
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Unit 5 Lesson 1 Solutions
What factors affect solubility?
• The solubility of a solute is its ability to dissolve
in a given amount of solvent at a certain
temperature and pressure.
• An increase in temperature has two effects on
most solid solutes—they dissolve more quickly,
and a greater amount can be dissolved in a given
amount of liquid solvent.
• The opposite is true for gases—an increase in
temperature makes a gas less soluble in water.
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Unit 5 Lesson 1 Solutions
What factors affect solubility?
• Pressure changes do not usually change the
solubility of solids or liquids.
• However, the solubility of a gas increases at
higher pressures and decreases at lower
pressures.
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Unit 5 Lesson 1 Solutions
What helps solids dissolve faster in
liquids?
• When a solid dissolves in a liquid, the particles of
the solid separate and spread out among the
particles of the liquid until the solid is evenly
distributed throughout the liquid. You cannot see
any solid particles in the final solution.
• An increase in temperature, an increase in surface
area, and an increase in motion can all help a
dissolving solid to dissolve more quickly. Each
method helps the solid particles separate and
spread out among the liquid particles.
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Unit 5 Lesson 1 Solutions
What helps solids dissolve faster in
liquids?
• Heating a mixture can help a solid dissolve very
quickly in a liquid.
• Crushing increases the surface area of solute that
is exposed to the liquid solvent. Crushing helps
solids dissolve faster.
• Solids also dissolve faster when you stir or shake
a mixture.
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