Science 7
Unit 3 Review
Section 7.1: How mixtures are Different from Pure Substances

State, define and give and or identify examples of the two types of mixtures.
o
Heterogeneous Mixtures: Mixtures
with two seperately
distinguishable parts. Both parts can be easily seen with the human eye
or with the aid of a microscope.
Example:__Salt and Sand____________________
o
Homogeneous Mixtures: Mixtures
with two or more completely
intermingled parts. Each part is indestinguishable as the mixture
appears to be one substance.
Example___Salt and Water____________________

What is a pure substance?
o
State, define and give and or identify examples of pure substances.

Pure substances consist of only one type of particle.
Example:__Iron_or Water______________________
o
Identify some pure substances.
1. __________________________
2. __________________________
3. __________________________
Q: Why is water a pure substance when it is composed of both oxygen and
hydrogen?
Since water molecules are considered only one type of particle
water is also considered a pure substance.
Q: How are pure substances and mixtures different?
Pure substances are made of one type of particle while mixtures consist
of more than one type of particle.
Section 7.2 : Classifying Mixtures

Describe the different types of heterogeneous mixtures and give examples of each.
1. Mechanical mixtures: Made up of two completely separate parts
2. Mixture of Mixtures: Consists of a combination of a homogeneous mixture
(ie. solution) combined with an undissolved component ie solid
Example__________Salt Water (solution) and Sand _______________
3. Suspension: Solid particles are suspended in a fluid
Example_________Milk or dirty water___________________________

What types of homogeneous mixtures are there?
o
The only type of homogeneous mixture is a solution. In a solution all parts
are completely intermingled (look like one part and cannot be easily
separated).

What are the four methods used to distinguish between homogeneous and
heterogeneous mixtures. See Below

Describe how you would identify if a substance was homogeneous or heterogeneous
1. Observation by eye: If you can see two parts –heterogeneous
2. Filtration- If there is a residue – heterogeneous
3. Microscope- If you can see microscopic pieces – heterogeneous
4. Tindale effect – If light passes straight through or you can see
through it - homogeneous
Section 8.1: Making Solutions: Solutes and Solvents
Use the terms dissolve, solute solvent and soluble when describing a
solution(homogeneous)
Ie. Salt is soluble in water, in a salt water solution salt is the solute while water is
the solvent
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________

What is a solute: The portion of a solution that gets dissolved

What is a solvent: The portion of a solution that does the dissolving.

What does it mean to say a substance is insoluble?
When a substance is insoluble it will not dissolve in a solute. For example sand
will not dissolve in water therefore the sand is insoluble.
Why can some substances dissolve while others cannot?
Substances dissolve when the particles in the substance ie sugar are more
strongly attracted to the particles in the solvent than themselves
Substances are insoluble when the particles in the substance are more strongly attracted to
themselves than to the solute. Ie pepper particles are more strongly attracted to pepper
particles than to water. Therefore pepper is not soluble in water- it will not dissolve.
Section 8.2 Concentration and Solubility
Q: What is the difference between a concentrated solution and a dilute solution?
A: A concentrated solution has a large amount of solute compared to solvent. Ie
Sweet Koolaid is concentrated because a lot of KoolAid has been dissolved. Weak
(watery) Kool Aid is dilute because much less Kool Aid has been dissolved.
Q The intensity of colour can be used
to compare the concentration of two or
more solutions. The illustration below
shows three cups of tea. Which cup
holds the most concentrated tea
solution? Which cup holds the most
dilute tea solution? Explain.
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
Q: What is a saturated solution vs an unsaturated solution.
A:
A saturated solution contains the maximum amount of dissolved solute. No more
solute can dissolve under the same conditions. Usually undissolved solute in the
mixture. An unsaturated solution has the ability to dissolve more solute.
How can you increase the rate of dissolving of a solute.
1. Stir the substance
2. Break the solute into pieces to increase the surface area
3. Increase pressure
Section 9.1: Separating Mixtures and Solutions
Given a mixture of different substances how can you separate them using properties
of each.
1.
Flotation:
When one part of the mixture is less dense (lighter) than water it
will float while the other sinks. Ie sawdust and sand
2.
Filtration: This separation technique depends on the size of the
particles. One substance has to be large enough to be trapped in a
filter.

Residue – The substance left in the filter

Filtrate – The substance that passes through the filter
3.
Magnetism:Used
4.
Evaporation: Used to separate a solution. The solvent evaporateds leaving the
to separate a magnetic substance from a non magnetic one.
solute behind
5.
Distillation: Used to seprate a solution. Involves the process of evaporating the
solute and then condensing it to collect.