In This Lesson:
Mixtures
(Lesson 2 of 6)
Today is Tuesday,
nd
February 2 , 2016
Pre-Class:
You know, I really like to save money whenever I
can. This year, I’m hoping to stop paying so
much for salt at the grocery store. So, the next
time I’m at the beach, I’m going to take some of
the salt out of the salt water.
Is that possible? How?
Today’s Agenda
• Types of matter
• Properties of matter
• Interactions of matter
– Also known as mixtures
• Where is this in my book?
– P. 44 and following…
By the end of this lesson…
• You should be able to classify matter based on
its composition.
• You should be able to determine the error of
measurements taken during a laboratory
process.
Types of Matter
• As you can imagine, having a definition as
broad as “has mass, takes up space” leads to
an awfully large amount of matter in the
world.
• More than just the phases of matter, chemists
have ways of classifying matter by its
composition.
Classifying Matter
MATTER
Pure
Substance
Element
Compound
Mixture
Homogeneous
Mixture
Heterogeneous
Mixture
Substances and Mixtures
MATTER
Pure
Substance
Physical
Separation
Mixture
• Mixtures can be separated by physical means.
– You’ll do this in a lab!
Substances
• Substances have:
– Uniform compositions
– Distinctive characteristics
– Examples:
Substance
• NaCl (Salt)
• Al (Aluminum)
• O2 (Oxygen)
Element
MATTER
Compound
Mixture
Elements and Compounds
• Elements are
substances that
cannot be broken
down into
components.
• Elements are
composed of only
one type of atom.
– Example:
• Hydrogen
• Oxygen
• Uranium
MATTER
Substance
Element
Compound
Mixture
Elements and Compounds
• Compounds are
composed of two or
more elements.
• Compounds can be
broken down
chemically.
– Example:
MATTER
Element
• Glucose (C6H12O6)
• Water (H2O)
• Carbon Dioxide (CO2)
Mixture
Substance
Compound
Chemical
Separation
Mixtures
• Mixtures are physical
blends of two or more
substances.
– Examples:
•
•
•
•
•
Salt water
Sand and water
Blood
Air
Vegetable soup
Substance
MATTER
Mixture
Homogeneous
Mixture
Heterogeneous
Mixture
Substances and Mixtures
• Homogeneous mixtures
MATTER
are also called solutions.
• They have a “single state”
Substance
Mixture
– in other words, it all
looks the same.
– Examples:
• Salt water
• Crystal Light
• Apple juice
Homogeneous
Mixture
Heterogeneous
Mixture
Substances and Mixtures
• Heterogeneous mixtures MATTER
are not uniform.
• They have more than one
Substance
Mixture
state – in other words,
it
doesn’t all look the same.
– Examples:
• Cookies and cream ice cream
• Fruit salad
• Vegetable soup
Homogeneous
Mixture
Heterogeneous
Mixture
Closure
• It’s time for the “Mixture or Substance” game!
– [cue 70’s game show music]
• I’ll show you a picture of a substance or
mixture, you tell me which one it is.
– Imaginary bonus points if you can identify
whether it’s an element or compound, or a
heterogeneous or homogeneous mixture.
• That sentence had many uses of the word “or.”
Classification of Matter
Is it a mixture or a substance?
Substance
Mixture
Mixture
Mixture
Mixture
Salt
Salt
Water
Air
Soil
Blood
Compound
Homogeneous
Homogeneous
Heterogeneous
Homogeneous
Classification of Matter
Is it a mixture or a substance?
Mixture
Substance
Mixture
Substance
Mixture
Sand
Water
Gasoline
Iron
Steel
Heterogeneous
Compound
Homogeneous
Element
Homogeneous
[Alloy]
Classification of Matter
Is it a mixture or a substance?
Substance
Mixture
Mixture
Mixture
Mixture
Aluminum
Sand
& Salt
Sand &
Water
Raisin
Bread
Brass
(copper
& zinc)
Element
Heterogeneous
Heterogeneous
Heterogeneous
Homogeneous
[Alloy]
Classification of Matter
Is it a mixture or a substance?
Mixture
Substance
Mixture
Mixture
Substance
Wood
Carbon
Dioxide
Cement
Candle
Wax
Sugar
Heterogeneous
Compound
Homogeneous
Homogeneous
Compound
Physical and Chemical Properties
• In addition to physical and chemical reactions,
like we learned about previously, there are
also physical and chemical properties.
– They work mostly the same way.
Physical and Chemical Properties
• Physical properties are those that can be
observed without actually causing a chemical
reaction.
• Examples:
– Density
– Hardness
– Melting/boiling points
– Color
– Smell
Important Physical Properties
of the States of Matter
http://www.suntrek.org/images/states.gif
Important Physical Properties
of the States of Matter
• Solids:
– Definite shape/definite volume
– Not easily compressed
• Liquids:
– Indefinite shape/definite volume
– Not easily compressed
• Gases:
– Indefinite shape/indefinite volume
– Easily compressed
Physical and Chemical Properties
• Chemical properties are those that cannot be
observed without actually causing a chemical
reaction.
• Examples:
– Flammability
– Corrosion (or rust-ability)
Intensive and Extensive Properties
• There are also properties considered intensive
and extensive.
• Intensive properties are those that apply to
any amount of a substance.
• Examples:
– Color
– Melting/boiling point
– Combustibility
Intensive and Extensive Properties
• Extensive properties are those that vary
based on the amount of a substance.
• Examples:
– Volume
– Length
– Mass
– Weight
Closure Part Deux
• Now let’s separate a mixture ourselves.
– Separation of a Mixture Lab
• There’s just one more thing you need…
Percent Error
• Today will be our first lab with a considerable
amount of calculations.
• Because we will all have slightly different
numbers, it’s important for us (and for
chemists) to be able to measure the accuracy
of the measurements we’ve taken.
Accuracy
• When measuring anything, there is usually some
error on the part of the scientist or the
equipment.
– The value calculated in the experiment is thus called
the experimental value.
• There is, of course, the “true” value; the one we
would expect to get if everything went perfectly.
• This is called the accepted value because
scientists have agreed that it is correct.
– Accepted value is sometimes called theoretical value,
ideal value, or expected value.
Percent Error
• Therefore, to find how far off we are from
what we should have gotten, we need to
calculate a statistic called percent error.
• Here’s the formula – be careful of order of
operations:
| Experiment al - Accepted Value |
Percent Error  (
) 100
Accepted Value
Percent Error Example
• You calculate the mass of an object to be 57.3
grams. However, your teacher tells you the
object is actually 59 grams. What is your
percent error?
| Experiment al - Accepted Value |
Percent Error  (
) 100
Accepted Value
| 57.3 - 59 |
Percent Error  (
)  100
59
Percent Error  2.88%
Closure
• You collect 23 mL of liquid in a graduated
cylinder. Unfortunately, the reaction you did
was only supposed to make 21.4 mL. What is
your percent error?
| Experiment al - Accepted Value |
Percent Error  (
) 100
Accepted Value
| 23 - 21.4 |
Percent Error  (
)  100
21.4
Percent Error  7.48%