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!

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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

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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

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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 =