Concept: Mixtures and Pure Substances

Concept: Mixtures and Pure Substances

UEQ: How does the structure of matter influence its physical and chemical behavior?LEQ: How is matter classified?

Bell Work 09/19/2012

Write question and answer.

Can you chemically break down an atom? Why or why not?

Too much energy is required to break an atom down into its protons, neutrons, and electrons alone. It would require a nuclear reaction to do this.

UEQ: UEQ: How does the structure of matter influence its physical and chemical behavior?LEQ: How is matter classified?

Bell Work 10/05/2012


Explain why is it easier to separate a heterogeneous mixture than a homogeneous mixture?

In a heterogeneous mixture, you can identify the components of the mixture

UEQ: In dealing with matter, how are composition, structure, properties and energy related? LEQ: How is matter classified?

Vocabulary Write word and definition.

Underline and highlight vocabulary word.

Write word on front and definition on back of index cards.

Create a poem or rap of vocabulary words and definitions.

Create foldable with words and definitions.

Create a crossword puzzle using words and definitions. Also make answer key!!!

Heterogeneousmixture

Homogeneousmixture

SolutionSoluteSolventSuspensionColloid


What are atoms? The smallest unit of an element

that maintains the chemical properties of that element


What is matter? Anything with mass and volume

(or takes up space) Matter can be broken into two

categories Pure Substances (1st) Mixtures


Pure Substances

Definite composition/uniform/unchanging

Pure substances can be broken down further into two more categories: elements and compounds


Elements A substance that cannot be

separated or broken down into simpler substances by chemical means

Found on periodic table


Compounds 2+ atoms chemically bound Must break bonds to get elemental form May form molecules

Water Carbon dioxide

Law of Definite Proportions The law that states that a chemical

compound always contains the same elements in exactly the same proportions by weight or mass


Mixtures Contains 2+ kinds of matter

physically mixedCan be physically separated Broken down into 2 main groups

Homogeneous Heterogeneous

UEQ: In dealing with matter, how are composition, structure, properties and energy related? LEQ: How can substances be identified as homogeneous or heterogeneous?

Homogeneous Mixtures Looks pure b/c evenly/uniformly mixed Also called a solution▪ Solid in liquid (salt water)▪ Gas in liquid▪ Solid in solid▪ Alloys-mixture of 2+ metals▪ Solid at room temperature


solutions▪ Solute – substance being dissolved (sugar)▪ Solvent – substance doing the dissolving

(water)

RULE OF THUMB!!! USUALLY YOU WILL HAVE MORE SOLVENT THAN SOLUTE!!!

What is solubility?▪ Amount of solute that can be dissolved▪ Concentration – high C – high solute/solvent,

low C – low solute/solvent


Heterogeneous Looks impure - Substances can be

identified Not uniform throughout b/c unevenly

mixed Examples: granite, wood, blood,

tossed salad Also called suspensions▪ Visible particles settle


Colloids Ex. Milk, fog, clay Look like a solution b/c particles do

not settle, but acts like a suspension b/c particles do not dissolve

How can you tell if it is a colloid?▪ Tyndall effect – scattering of light by

particles in a mixture


Solution

Colloid Suspension

Does it settle?

No No yes

Can it be filtered?

No No Yes

Does it scatter light?

No Yes Yes


Bell Work 10-08-2012

Write Question and AnswerHow can you tell a solution,

suspension, and colloid apart from one another? Differentiate between the 3.


Bell Work 09-21-2012Write Question and AnswerHow can you tell a solution, suspension, and colloid

apart from one another? Differentiate between the 3.Solution is a homogeneous mixture where particles are

uniform throughout and does not settle. Suspensions are heterogeneous mixtures that have particles that settle and it is not uniform throughout. Colloids fall in between solutions and suspensions in that it has particles that do not settle (like solutions); but, the particles do not dissolve (like in suspensions). You can also use the Tyndall effect to differentiate colloids from solutions because colloids will scatter the light.

UEQ: In dealing with matter, how are composition, structure, properties and energy related? LEQ: How can the components of mixtures be separated?

Methods for separating mixtures Distillation Filtration Chromatography


Distillation Separating mixture by using differences in

boiling points Good for separating solutions How? Heat mixture to the b.p. of the substance

with the lowest b.p. This will create a vapor first. Collect and condense into a liquid in a separate container. Continue process if solution contains more than 2 substances.


Filtration Separating solid from liquid Use porous barrier to separate


Chromatography Separation technique that identifies

parts of a mixture by how fast compounds move across a material

Greatest attraction moves the fastest



Explain how you could separate sand and salt.

You could first add water to the solid mixture to form salt water. Filter the salt water from the sand. This will leave sand in the filter and salt water in the container. Then, through distillation process, heat the salt water to the water’s boiling point so that you can collect and condense water vapor in separate container leaving only salt behind.

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Concept: Mixtures and Pure Substances