Why Does Matter Matter?
TEKS
• 4 (A) differentiate between physical and
chemical changes and properties;
• 4 (B) identify extensive and intensive
properties;
• 4 (D) classify matter as pure substances or
mixtures through investigation of their
properties.
Physical vs. Chemical
Changes
• Examples:
– rusting iron
• Chemical
– dissolving in water
• Physical
– burning a log
• Chemical
– melting ice
– grinding spices
• Physical
• Physical
Sure Signs of a Chemical
Change
• Energy Change
(Temperature and
Light)
• Gas Produced (not
from boiling!)
• Precipitate – a solid
formed by mixing
two liquids together
• Color Change (Be
Careful)
http://jchemed.chem.wisc.edu/JCESo
ft/CCA/CCA0/MOVIES/S1047.MOV
Physical Changes
– can be observed without
changing the identity of
the substance
Some physical changes
would be
• Phase Change
– boiling of a liquid
– melting of a solid
• dissolving a solid in a
liquid to give a
homogeneous mixture
— a SOLUTION.
Changes Quiz
Are the following changes considered chemical
or physical?
• 1. Sharpening a pencil
• 2. Dissolving Koolaid in water
• 3. Silver Tarnishing
• 4. Alcohol evaporating
• 5. Milk souring
Chemical Properties and
Chemical Change
•Burning hydrogen (H2) in
oxygen (O2) gives H2O.
• Chemical change or
chemical reaction —
transformation of one or
more atoms or molecules
into one or more different
molecules.
Physical
Properties (
see STAAR
field guide)
What are some physical
properties?
• color
• melting and boiling
point
• odor
Graphite —
layer
structure of
carbon
atoms
reflects
physical
properties.
Physical vs. Chemical
Properties
• Examples:
– melting point
physical
– flammable
chemical
– density
physical
– magnetic
physical
– tarnishes in air
chemical
Physical Chemical Properties
quiz
1.
2.
3.
4.
5.
6.
7.
8.
Combustible
Hard
13 Kilograms
Boils at 200°C
Density of 6.1g/cm³
Corrodes in air
Soluble in water
Volatile in water
Chemical
Physical
Physical
Physical
Physical
Chemical
Physical
Chemical
What are Extensive and
Intensive Properties?
All Physical Properties of Matter can be classified as
Extensive or Intensive.
• Extensive Properties- depend on the amount of matter
Ex) Mass
• Intensive Properties- DOES NOT depend on the
amount of matter.
Ex) luster, density (Mass/Volume ratio)
Determine Extensive or Intensive from the Physical
properties on slide 9.
Intensive/Extensive Properties
Quiz
•
•
1.
2.
3.
4.
Hard
13 Kilograms
Boils at 200°C
Density of 6.1g/cm³
Corrodes in air
Soluble in water
Mixtures and Pure Substances
• Matter can be classified as a
mixture or a pure substance.
Mixtures
• A mixture has variable composition
• • A homogeneous mixture has the same
properties throughout.
• A heterogeneous mixture has different properties
in different parts of the mixture.
Separation of Mixtures
distillation
filtration
Separation of Mixtures
Decantation- is a process of carefully
pouring a solution from a container in
order to leave the precipitate
(sediments) in the bottom of the
original container.
Chromatography- involves passing a mixture
dissolved in a "mobile phase" through a
stationary phase. Chromatography works on
the principle that different compounds will
have different solubilities and adsorption to
the two phases, which will allow for their
separation.
Pure Substances
A pure substance always has the same
composition.
• Pure substances are of two types:
Elements which cannot be broken down chemically
into simpler substances
Compounds which can be chemically broken down
into elements
Water is a compound. All the
components are the same—H2O molecules.
Matter Flowchart
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
Can it be physically
separated?
PURE SUBSTANCE
no
Heterogeneous
Mixture
yes
Can it be chemically
decomposed?
Compound
no
Element
How can it be separated ? How can it be separated ?
Filtration
Chemically
Distillation
Electrolysis
Chromatography
Nuclear Reaction
Types of Mixtures
• Variable combination of 2 or more
pure substances.
Heterogeneous –
visibly separate phases
Homogeneous –
Same throughout