matter: properties & change
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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 - PowerPoint PPT PresentationTRANSCRIPT
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