pure substances vs. mixtures

PURE SUBSTANCESVS.

MIXTURESPENTONEY 2017

WHAT IS A PURE SUBSTANCE?

Classification of matter that includes elements, molecules and

compounds

Cannot be separated by physical means such as distillation,

filtration, or sifting.

CHEMISTRY: MIXTURES AND PURE SUBSTANCES

Pure substance:

1. Element

2. Molecule

3. Compound

Not one of those? NOT A PURE SUBSTANCE!

CHEMISTRY: MIXTURES AND PURE SUBSTANCES

ELEMENT:

One or more of the same type of atom.

Ex: N N2

Both of these examples are called an element as we only have the element

Nitrogen (N) and nothing else.

CHEMISTRY: MIXTURES AND PURE SUBSTANCES

COMPOUND:

Two or more atoms chemically combined, at least one is

different.

Ex: CO2 (Carbon Dioxide) NaCl (salt)

Both of these examples are types of compounds.

CHEMISTRY: MIXTURES AND PURE SUBSTANCES

MOLECULE: 2 or more atoms chemically

combined.

Ex: N2 N3 H2O

CHEMISTRY: MIXTURES AND PURE SUBSTANCES

Ex: N2 N3

(These molecules are more specifically called an

“Element” because they are made up of only one type

of atom.)

*CHEMISTRY: MIXTURES AND PURE SUBSTANCES

Ex: H2O

(This is also a molecule, as it has 2 or more atoms

combined. But its more specific name is a compound. )

CHEMISTRY: MIXTURES AND PURE SUBSTANCES

The words “ELEMENT” and “COMPOUND” are specific types

of molecules.

ALL OF THE BOXES BELOW SHOW AN EXAMPLE OF A PURE SUBSTANCE

ELEMENT (C) ELEMENT (O2) COMPOUND (CO2)

CHEMISTRY: MIXTURES AND PURE SUBSTANCES

Examples of pure substances:

Salt (NaCl)

Sugar C6H12O6 (Glucose = Sugar)

H2O (Water)

ELEMENTS (like gold, silver, oxygen, nitrogen…any

on the periodic table)

CHEMISTRY: MIXTURES AND PURE SUBSTANCE

MIXTURE: two or more pure substances thrown

together. All substances keep their own identities.

*Example: When I mix sugar and water, I get the mixture sugar-water.

The sugar still has its own identity (it is sweet), the water still has its own

identity (its still water). Nothing new is created, and both can be

separated physically (boiling).

CHEMISTRY: MIXTURES AND PURE SUBSTANCE

There are two types of mixtures:

1. Homogenous

2. Heterogeneous

CHEMISTRY: MIXTURES AND PURE SUBSTANCE

Homogenous Mixture: Evenly mixed mixture

Examples:

Milk

Air (a mixture of gases you breath in)

Soda

Juice

WHAT IS A HOMOGENOUS MIXTURE?

• A mixture that is evenly distributed

• Commonly called solutions.

• Solution = Solute + Solvent

Solute: “stuff” being dissolved

Solvent: “stuff” doing the dissolving

• The solvent is present in greater quantity

• The solute is present in the lesser quantity

• Ex: Salt water: Salt = solute, Water = solvent

CHEMISTRY: MIXTURES AND PURE SUBSTANCE

Heterogeneous Mixture: Unevenly mixed mixture.

Example:

Salad

Legos

Cookie dough ice-cream

Chicken noodle soup

CHEMISTRY: MIXTURES AND PURE SUBSTANCE

ALL MIXTURES ARE PHYSICALLY COMBINED AND

CAN BE PHYSICALLY SEPARATED.

CHEMISTRY: MIXTURES AND PURE SUBSTANCE

Ways to physically separate a mixture:

• Boiling: evaporates liquid

• Sifting: Picking out pieces (like in cookies dough ice-cream =) )

• Filtering: Just like a pool filter, it takes out unwanted things.

*CHEMISTRY: MIXTURES AND PURE SUBSTANCE

What is the biggest differences between a mixture and a pure substance?

Mixtures Pure substance

Are physically mixed

together

Chemically combined

(bonded)

Can be physically

separated

Must be chemically

separated

(COPY CHART)

CLASSIFYING MATTER

Matter

Pure Substances Mixtures

Elements Compounds

Homogeneous Heterogeneous

Fe, OH2O, CO2

milk, tea Rocky Road ice

cream, muddy

waterMolecules

Fe2

(COPY CHART)

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 1:

Which substance is not a compound?

a. Ne c. SiO2

b. HCN d. H2O2

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 1:

Which substance is not a compound?

a. Ne c. SiO2

b. HCN d. H2O2

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 2:

The components of a homogeneous mixture could be described as

a. inseparable c. chemically bonded

b. evenly mixed d. unevenly mixed

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 2:

The components of a homogeneous mixture could be described as

a. inseparable c. chemically bonded

b. evenly mixed d. unevenly mixed

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 3:

Iron filings are thrown into a pile of sand. What is the best way to

separate this mixture?

A. Use a magnet to pick up the sand.

B. Sift through the sand for all of the iron.

C. Use a magnet to pick up the iron filings.

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 3:

Iron filings are thrown into a pile of sand. What is the best way to

separate this mixture?

A. Use a magnet to pick up the sand.

B. Sift through the sand for all of the iron.

C. Use a magnet to pick up the iron filings.

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 4:

A substance contains two components joined by physical means. Which

best describes the substance?

A. element

B. compound

C. mixture

D. molecule

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 4:

A substance contains two components joined by physical means. Which

best describes the substance?

A. element

B. compound

C. mixture

D. molecule

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 5:

Which best describes water?

A. a compound

B. an element

C. a heterogeneous mixture

D. a homogeneous mixture

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 5:

Which best describes water?

A. a compound

B. an element

C. a heterogeneous mixture

D. a homogeneous mixture

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 6:

Which image below is a mixture?

A B C D

CHEMISTRY: MIXTURES AND PURE SUBSTANCE REVIEW

Question 6:

Which image below is a mixture?

A B C D

Element Compound molecule mixture of elements +

compounds