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Quick Review

• Units! Units! Units!

– Make sure your units cancel out in conversions

• Show your work

• Significant figures

– Watch your zeros

– Remember the rules for addition/subtraction and

multiplication/division

– Do NOT consider conversion factors when determining

significant figures

• Answer will have same number of significant

figures as original question

– Exact numbers have an infinite number of significant

figures

Physical and Chemical

Properties and Changes

Chapter 1 and 2

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Scientific Method• Hypothesis – A descriptive model used to explain

observations – must be testable

• Scientific Theory – A thoroughly tested hypothesis that explains why experiments give certain results - cannot be proven as absolute truth

• Scientific Law – A concise statement that summarizes the results of a variety of observations and experiments (what happens)

• Describes a natural phenomenon

• Mathematical relationship

3 Specific Laws

• Law of Conservation of Mass

– In any physical or chemical reaction, mass is neither created nor destroyed. It is conserved.

• Law of Conservation of Energy

– In any chemical reaction, E is neither created nor destroyed. E can be converted from one form to another.

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• Law of Conservation of Matter and Energy

– Matter and E are interchangeable under special conditions.

• Nuclear reactors and particle accelerators

ENERGY

• The capacity for doing work.

• All chemical and physical changes involve absorption or emission of energy

• Forms – light, electrical, thermal, nuclear, mechanical, chemical

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More energy

• Potential Energy

– Stored E

– E of position

• Kinetic Energy

– E in motion

– P.E. is converted into K.E.

– Ex. Gasoline � chemical P.E.

– Burned in car � K.E.

– Ex. Boulder at top of hill

Endothermic Reaction

• Heat of product higher than reactant.

• Heat absorbed.

• Taken in

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Exothermic Reaction

• Heat of reactants higher than products.

• Heat given off.

Matter• Anything that has mass or takes up space

• Two types of Matter1. Pure substances – specific kind of matter with uniform and

definite composition

• Elements – Na, Cl, F, C

• Compounds – NaCl, H20, Fe2O3

2. Mixtures – Physical blend of 2 or more substances which have definite composition. Can be separated into elements and compound.

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Homogeneous

Mixture (Solution)

Air Soda Brass

Can be a solid, liquid

or gas

Can be separated

into its components

Uniform

composition

Combination of

substances that is the

same throughout

Heterogeneous

Mixture

GraniteChocolate chip

cookieOcean

Composition varies

from region to region

Can observe distinct

components

Can be separated

into its components

Combination of

substances that is not

the same throughout

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Physical Property• A quality of a substance that can be measured or

observed.

• In order for a property to be a physical property,

you must be able to observe it through one of your

senses.

Here Are Some Examples of The Properties of Matter

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Examples of Physical

Properties

• Texture: Rough

• Color: Orange

• Shape: Cone

• Odor: Barely Detectable

• Measurable properties such as mass and length

Intensive Physical Properties

• Independent of the amount of matter in a substance; the same no matter what the quantity.

• Examples: Density, color, boiling point, atomic weight, conductivity, luster, smell, and malleability.

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Extensive Physical Properties

• Dependent on the amount of matter in a

substance; differs according to the quantity.

• Examples: Volume and mass.

Chemical Property

• Behavior of a substance as it undergoes

chemical reactions.

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Examples of Chemical Properties

• Flammability:

Extremely High

• Solubility: Varies

• Reactivity: Depends

on Temp.

Example of Physical and Chemical Properties

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Physical Changes

• A change in which no alteration is made in

the chemical composition.

• Examples: Breaking glass, cutting wood, or

changes in state.

Chemical Changes

• Changes that alter the atomic structures and

compositions of the substances involved;

different properties result.

• Examples: Rust, decay, and fermentation.

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Chemical Change

Indicators

• Heat is either given off or absorbed.

• Evolution of a gas.

• Color change.

• Formation of a precipitate (solid).

Methods of Physical Separation

1. Filtration – separates liquids from solids by

using filter paper

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Methods of Physical Separation

2. Decantation – to pour off

3. Distillation

• a method for separating the components of a liquid

mixture that depends on differences in the boiling

points of the components.

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4. Chromatography

• a method of separating

components of a gas

or liquid. It uses

differences in

solubility to separate

into bands on a paper,

thin layers of solvents,

or a column of beads.

5. Sublimation

• the process by which a substance goes

directly from solid to vapor state without

passing through the liquid state.

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The End