Matter: Properties & Change

Chapter 3

Matter

• Matter – anything that has mass and takes up space

– Everything around us

• Chemistry – the study of matter and the changes it undergoes

Four States of Matter

• Solids– particles vibrate but can’t

move around

– fixed shape

– fixed volume

– incompressible

Four States of Matter

• Liquids– particles can move

around but are still close together

– variable shape (shape of container)

– fixed volume– virtually

incompressible

Four States of Matter

• Gases– particles can separate and

move throughout container– variable shape– variable volume– easily compressed– vapor = gaseous state of a

substance that is a liquid or solid at room temperature

Four States of Matter

• Plasma– particles collide with enough

energy to break into charged particles (+/-)

– gas-like, variableshape & volume

– stars, fluorescentlight bulbs

Physical Properties

• Physical Property

can be observed without changing the identity of the substance

Physical Properties

• Physical properties can be described as one of 2 types:

• Extensive Property

depends on the amount of matter present (example: length)

• Intensive Property

depends on the identity of substance, not the amount (example: density)

Chemical Properties• Chemical Property

describes the ability of a substance to undergo changes in identity

Physical vs. Chemical Properties

• Examples:

– melting point

– flammable

– density

– magnetic

– tarnishes in air

physical

chemical

physical

physical

chemical

Physical Changes

• Physical Change

– changes the form of a substance without changing its identity

– properties remain the same

• Examples: cutting a sheet of paper, all phase changes

Phase Changes

Evaporation =

Condensation =

Melting =

Freezing =

Sublimation =

Deposition =

Liquid Gas

Gas Liquid

Solid Liquid

Liquid Solid

Solid Gas

Gas Solid

Chemical Changes

• Process that involves one or more substances changing into a new substance– Commonly referred to as a chemical

reaction– New substances have different

compositions and properties than the original substances

Chemical Changes

• Signs of a Chemical Change

– change in color or odor

– formation of a gas

– formation of a precipitate (solid)

– change in temperature

Physical vs. Chemical Changes

• Examples:

– rusting iron

– dissolving in water

– burning a log

– melting ice

– grinding spices

chemical

physical

chemical

physical

physical

Law of Conservation of Mass

• Although chemical changes occur, mass is neither created nor destroyed in a chemical reaction

• Mass of reactants equals mass of productsmassreactants = massproducts

A + B C

Conservation of Mass• In an experiment, 10.00 g of red mercury (II)

oxide powder is placed in an open flask and heated until it is converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of the oxygen formed in the reaction?

Mercury (II) oxide mercury + oxygenMmercury(II) oxide = 10.00 gMmercury = 9.26Moxygen = ?

GIVEN:Mercury (II) oxide mercury + oxygen

mmercury(II) oxide = 10.00 g

mmercury = 9.86 g

moxygen = ?

WORK:10.00 g = 9.86 g + moxygen

moxygen = (10.00 g – 9.86 g)

moxygen = 0.74 g

massreactants = massproducts

Matter Flowchart

MATTER

Can it be physically separated?

Homogeneous Mixture(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

Matter Flowchart

• Examples:

– graphite

– pepper

– sugar (sucrose)

– paint

– soda

element

heterogeneous

mixture

compound

heterogeneous

mixture

solution

Pure Substances

• Element– composed of identical atoms– Example: copper wire, aluminum foil

Pure Substances

• Compound

– composed of 2 or more elements in a fixed ratio

– properties differ from those of individual elements

– Example: table salt (NaCl)

Mixtures

• Variable combination of 2 or more pure substances.

Heterogeneous Homogeneous

Mixtures

• Solution– homogeneous– very small particles– particles don’t settle– Example: rubbing alcohol

Mixtures

• Heterogeneous– medium-sized

to large-sized particles

– particles may or may not settle

– Example: milk, fresh-squeezed lemonade

Mixtures

• Examples:

– tea

– muddy water

– fog

– NaCl & H2O

– Italian salad dressing

• Answers:– Solution

– Heterogeneous

– Heterogeneous

– Solution

– Heterogeneous

Separating Mixtures• Substances in a mixture are

physically combined, so processes bases on differences in physical properties are used to separate components

• Numerous techniques have been developed to separate mixtures to study components– Filtration– Distillation– Sublimation– Crystallization– Chromatography

Filtration

• Used to separate heterogeneous mixtures composed of solids and liquids

• Uses a porous barrier to separate the solid from the liquid

• Liquid passes through leaving the solid in the filter paper

Distillation• Used to

separate homogeneous mixtures

• Based on differences in boiling points of substances involved

Sublimation

• Process during which a solid changes to a vapor without melting

• Can be used to separate two solids present in a mixture when one of the solids sublimates but the other does not

Crystallization• Separation technique

that results in the formation of pure solid particles from a solution containing the dissolved substance

• As one substance evaporates, the dissolved substance comes out of solution and collects as crystals

• Produces highly pure solids

• Rocky candy is an example of this

Chromatography• Separates components of a

mixture based on ability of each component to be drawn across the surface of another material

• Mixture is usually liquid and is usually drawn across chromatography paper

• Separation occurs because various components travel at different rates

• Components with strongest attraction for paper travel the slowest; components with strongest attraction for the liquid travel the fastest

Separation of a CompoundSeparation of a CompoundThe Electrolysis of Water

Water Hydrogen + Oxygen

2 H2O 2 H2 + O2

Reactant Products

Compounds must be separated by chemicalchemical means.

With the application of electricity, water can be separated into its elements