ChemCh2.2.ppt

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2.2 Mixtures >

1 .

Chapter 2 Matter and Change

2.1 Properties of Matter

2.2 Mixtures

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2 .

Coffee is often

brewed by mixing

hot water with

ground coffee

beans.

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2.2 Mixtures >

3 .

Describing Matter

Classifying Mixtures

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4 .

Describing Matter

• _{A salad bar provides a range of items, such as}

lettuce, tomatoes, cheese, and green peppers.

• Customers choose which items to use in their

salads and how much of each item to use.

• _{So, each salad mixture has different types and}

amounts of components.

– A

mixture

is a physical blend of two or more

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5 .

Describing Matter

Most samples of matter are mixtures.

• _{Some mixtures are easier to recognize}

than others.

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6 .

Describing Matter

Recognizing air as a mixture of gases is

more difficult.

• _{But the fact that air can be drier or more}

humid shows that the amount of one

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7 .

Describing Matter

Based on the distribution of their

components, mixtures can be

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8 .

Describing Matter

Heterogeneous Mixtures

In chicken noodle soup, the ingredients in

the soup are not evenly distributed

throughout the mixture.

• _{There is likely to be different amounts of}

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9 .

Describing Matter

A mixture in which the composition is not

uniform throughout is a heterogeneous

mixture.

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10 .

Describing Matter

Homogeneous Mixtures

The substances in the

olive oil are evenly

distributed throughout

the mixture.

• _{So, olive oil doesn’t}

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11 .

Describing Matter

Homogeneous Mixtures

The same is true for

vinegar.

• _{Vinegar is a mixture of}

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12 .

Describing Matter

Homogeneous Mixtures

Olive oil and vinegar

are homogeneous

mixtures.

• _A

_homogeneous

mixture

is a mixture in

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13 .

Describing Matter

Homogeneous Mixtures

Olive oil and vinegar

are homogeneous

mixtures.

• _A

_homogeneous

mixture

is a mixture in

which the composition

is uniform throughout.

• _{Another name for a homogeneous mixture is a}

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14 .

Describing Matter

Homogeneous Mixtures

Many solutions are liquids.

• _{But some are gases, like air.}

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15 .

Describing Matter

Homogeneous Mixtures

The term phase is used to describe any

part of a sample with uniform composition

and properties.

• _{By definition, a homogeneous mixture consists of}

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16 .

Describing Matter

• _{When oil and vinegar}

are mixed, they form

a heterogeneous

mixture with two

layers, or phases.

• The oil phase floats

on the water, or

vinegar, phase.

A heterogeneous

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17 .

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18 .

At the beach, you realize that both

ocean water and sand are mixtures.

Which is a homogeneous mixture (or

solution)? Which is a heterogeneous

mixture?

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19 .

Separating Mixtures

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20 .

Separating Mixtures

If you have a salad containing an

ingredient you don't like, you can

remove it with a fork.

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21 .

Separating Mixtures

• _{To separate a mixture of olive oil and}

vinegar, for example, you could decant, or

pour off, the oil layer.

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2.2 Mixtures >

22 .

Separating Mixtures

• _{To separate a mixture of olive oil and}

vinegar, for example, you could decant, or

pour off, the oil layer.

• Or, you might cool the mixture until the oil

turned solid.

– Pouring off the oil layer takes advantage of the fact

that oil floats on water.

– Cooling until the oil layer turns solid takes

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23 .

Separating Mixtures

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24 .

Filtration

Separating Mixtures

The coffee filter at right can

separate ground coffee

beans from brewed coffee.

• _{The liquid brewed coffee}

passes through the paper

filter, but the solid coffee

grounds cannot pass

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25 .

Filtration

Separating Mixtures

Filter paper used in a laboratory is similar

to coffee filters.

• _{Filter paper is often placed in a funnel.}

• Then the mixture is poured into the funnel.

• Solid particles that cannot pass through the

filter remain in the funnel.

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26 .

Filtration

Separating Mixtures

The process that separates a solid from a

liquid in a heterogeneous mixture is

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27 .

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Brewed coffee is a mixture of ground

coffee beans and water. What process

is used to separate ground coffee

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2.2 Mixtures >

28 .

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&

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Brewed coffee is a mixture of ground

coffee beans and water. What process

is used to separate ground coffee

beans from brewed coffee?

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29 .

Distillation

Separating Mixtures

Tap water is a homogeneous mixture of

water and substances that are dissolved

in the water.

• _{One way to separate water from the other}

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30 .

Distillation

Separating Mixtures

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31 .

Distillation

Separating Mixtures

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32 .

Distillation

Separating Mixtures

As water in the distillation flask is heated, water vapor forms,

rises in the flask, and passes into a glass tube in the condenser.

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33 .

Distillation

Separating Mixtures

As water in the distillation flask is heated, water vapor forms,

rises in the flask, and passes into a glass tube in the condenser.

• The tube is surrounded

by cold water, which

cools the vapor to a

temperature at which it

turns back into a liquid.

• The liquid

water is

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34 .

Distillation

Separating Mixtures

The solid substances that were dissolved in the water

remain in the distillation flask.

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35 .

Sample

Problem 2.1

Sample

Problem 2.1

Separating a Heterogeneous Mixture

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36 .

In order to identify how to separate

aluminum and iron nails, the properties of

both aluminum and iron must be known.

Sample

Problem 2.1

Sample

Problem 2.1

Analyze

Identify the relevant concepts.

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37 .

Sample

Problem 2.1

Sample

Problem 2.1

Solve

Apply concepts to this situation.

2

List the properties of each substance in

the mixture.

Aluminum

• metal

• gray color

• doesn’t dissolve

in water

• not attracted to

magnet

Iron

• metal

• gray color

• doesn’t dissolve

in water

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38 .

Sample

Problem 2.1

Sample

Problem 2.1

Solve

Apply concepts to this situation.

2

Identify a property that can be used to

separate different substances from each

other.

• _{The ability to be attracted by a magnet is a}

property that iron and aluminum do not

share.

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39 .

Which physical property does

filtration rely on to separate

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40 .

Which physical property does

filtration rely on to separate

mixtures? Which does distillation

rely on?

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41 .

Key Concepts

Mixtures can be classified as

heterogeneous mixtures or as

homogeneous mixtures, based on the

distribution of their components.

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42 .

• mixture

: a physical blend of two or more

substances that are not chemically combined

• heterogeneous mixture

: a mixture that is not

uniform in composition; components are not

evenly distributed throughout the mixture

• homogeneous mixture

: a mixture that is

uniform in composition; components are

evenly distributed and not easily distinguished

• solution

: a homogeneous mixture; consists of

solutes dissolved in a solvent

Glossary Terms

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43 .

• phase

: any part of a sample with uniform

composition and properties

• filtration

: a process that separates a solid

from the liquid in a heterogeneous mixture

• distillation

: a process used to separate

components of a mixture using differences in

boiling points

Glossary Terms

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44 .

END OF 2.2