february [4(5) - 10], 2009 1.what does it mean for an object to have indefinite volume? what state...
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February [4(5) - 10], 2009
1. What does it mean for an object to have indefinite volume? What state or states of matter have indefinite volume?
2. How can we use physical properties to differentiate matter?
Agenda
• Do Now/Announcements• When Love is in the Air…Mixture
Mania!• When Love Grows Cold…
Separation Anxiety• Independent Work Time• Exit Ticket
Objectives
• SWBAT distinguish between pure and impure substances (mixtures).
• SWBAT determine if a mixture is homogeneous or heterogeneous.
• SWBAT develop a plan to separate mixtures.
What is a PURE SUBSTANCE?
• A pure substance is a form of matter that has a uniform and unchanging composition
• A pure substance has a definite composition and distinct properties
Uniform = constant, consistent
Think about your school uniforms!
Add to Vocabulary Log!Add to Vocabulary Log!
Examples ofPURE SUBSTANCES
• Elements: – Gold, Carbon, Nitrogen
• Compounds: – Water (H2O)
– Carbon Dioxide (CO2)
• “Pure Honey” or “Pure Silk” are not really pure in the scientific sense
What is an IMPURE SUBSTANCE?
• A impure substance is a form of matter with more than one phase (or part)
– A phase is a section of matter
• Most substances that we interact with are impure substances.
• Impure substances are also known as mixtures
Add to Vocabulary Log!Add to Vocabulary Log!
Examples ofIMPURE SUBSTANCES
Food ProductsChocolate milk, apple pie, nachos
Examples ofIMPURE SUBSTANCES
Building MaterialsMDF (like wood), steel (carbon and
iron), grout
Examples ofIMPURE SUBSTANCES
JewelrySterling silver, 14 karat gold, platinum
Alloys are Alloys are stronger than stronger than
individual individual metals!metals!
What is a MIXTURE?
• A mixture is a combination of one or more pure substances
– Each substance keeps it own chemical properties
– Physically blended– Can potentially be separated
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Examples of MIXTURESKool-AidChocolate milkTrail mixOrange juice with
pulpForestWedding bouquetSaladThe air we breathe
Types of MIXTURES
• Homogeneous mixtures• Heterogeneous mixtures• Alloys (Extra Info!)
HOMOGENEOUS MIXTURES
• What does homo- mean?• HOMO- is a prefix that means
“the same”• So a homogeneous mixtures is
a mixture that has constant composition throughout the mixture
– Has only one phase – Also known an solutionsAdd to Vocabulary Log!Add to Vocabulary Log!
Examples ofHOMOGENEOUS MIXTURES
Kool-AidSalt Water
Sugar WaterTap Water
Air
HOMOGENEOUS MIXTURES
ONE PHASE
Does the Kool-Aid look the same all the way from the top to the
bottom?
HOMOGENEOUS MIXTURES
The AIR we breathe is ahomogeneous mixture.
HETEROGENEOUS MIXTURES
• What does hetero- mean?• HETERO- is a prefix that means
“different” or “other”• So a heterogeneous mixtures
is a mixture that does not have constant composition throughout the mixture
– Has more than one phase– Phases remain distinct from each
otherAdd to Vocabulary Log!Add to Vocabulary Log!
Examples ofHETEROGENEOUS MIXTURES
Trail mixOatmeal raisin
cookieSand and waterOrange juice with
pulpSaladWedding Bouquet
HETEROGENEOUS MIXTURES
MORE THAN ONE PHASE
Cookie dough
Raisin
HETEROGENEOUS or HOMOGENEOUS?
HOMOGENEOUS
HETEROGENEOUS
ONE PHASE MORE THAN ONE PHASE
HETEROGENEOUS or HOMOGENEOUS?
HOMOGENEOUS
HETEROGENEOUS
ONE PHASEMORE THAN ONE PHASE
SEPARATION OF MIXTURES
Remember! Mixtures are
PHYSICALLY BLENDED!This means that they can be
PHYSICALLY SEPARATED!
Why Do Scientists Care About Separating Mixtures?
Separation science helps us find out what is in the matter that
we interact with everyday!
• Food• Medicines• Soaps
What if you were allergic to a certain substance and you
would die if you ate it? What if it is just a small part of the food you eat? Example: Gluten
Why Do Scientists Care About Separating Mixtures?
Separation science helps us purify things such as…
• Water• Food• Air• Lotions• Soaps
What if the chemical plants all
around us were allowed to emit all their by-products…some toxic, some
safe?
Example:
Chemical Waste
What if our water was not purified?
Example:
Drinking Sewer Waste
HOW TO SEPARATE MIXTURES?
It all has to do with
PHYSICAL PROPERTIES!!!
1. Separation based on color, shape, texture, size, etc.
2. Magnetic separation3. Separation by filtration4. Mystery Separation Technique
COLOR, SHAPE, TEXTURE, SIZE, etc.
Look at the color, shape,texture, and size of the
objectsin Mixture #1 (in Ziplock).
How can you separate theseitems?
Now, SEPARATE!
MAGNETIC SEPARATION
Magnetism describes the the
properties of attractionpossessed by magnets
MAGNETISM
Look at Mixture #3.Do you see anything that
might be magnetic?How can you separate the
mixture?Now, SEPARATE!
FILTRATION Separates SOLIDS
from LIQUIDS!
FILTRATION – Up Close!
FILTRATION
Look at Mixture #2.How can you separate this?
Now, let’s learn how!Now, SEPARATE!
Separates MAGNETIC objects from NON-MAGNETIC objects!
MYSTERY SEPARATION
Look at Ms. Stroh’s Mixture.How can we separate the
mixture?What physical property is
different about the two substances in the
mixture?
MYSTERY SEPARATION
DENSITY!Separates objects that have different densities!
Independent Work TimePlease complete the Worksheet and turn in before you leave.
If you don’t finish, complete for homework.Answer these questions on the back:
1. Is “pure honey” pure in the scientific sense? Why or why not?
2. Plain hot chocolate is a _______ mixture.3. Hot chocolate with marshmallows is a
____________ mixture.4. Develop a plan to separate a mixture of
water, small pebbles, and iron shavings. You know that the density of the pebbles is greater than 1.0 g/mL and that the iron shavings are magnetic. Go!
Exit Ticket
1. What is one difference between homogeneous and heterogeneous mixtures?
2. Which of the following is the heterogeneous mixture?
a) Lemonadeb) Tap waterc) Broccoli and cheese soupd) Creamy peanut butter
3. How could you separate a mixture of sand and milk? (Think about one of the four we learned about today.)
Extra Info!ALLOYS
• An alloy is a homogeneous mixture of metals
Metal #1 + Metal #2 --> ALLOY• Examples
– Steel = Carbon + Iron– Brass = Copper + Zinc– Bronze = Copper + Tin– Gold Jewelry– Sterline Silver = Silver + Nickel + Copper– Nitinol =
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