matter and change mrs. mcguire chemistry. a) classification of matter some criteria for the...
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Matter and Change
Mrs. McGuire
Chemistry
A) Classification of MatterSome Criteria for the Classification of Matter Properties
State (solid, liquid, gas)
Composition
Properties
Intensive
-Do not depend on amount of matter.Ex: color, odor, luster and conductivity
Extensive
-Depend on amount of matter.Ex: mass, length, and volume
Intensive and Extensive Properties
Sulfur
Properties
Physical: observed without changing the composition of the substance.
Chemical: the ability of a substance to undergo a specific chemical change
REGENTS QUESTION
Which statement describes a chemical property of sodium?
(1) Sodium has a melting point of 371 K.
(2) Sodium has a molar mass of 23 grams.
(3) Sodium can conduct electricity in the
liquid phase.
(4) Sodium can combine with chlorine to
produce a salt
Examples of Physical PropertiesColor, odor, hardness, density,
melting point, boiling point, state, solubility.
Substance State Color Melting
Point (C°)
Boiling Point (C°)
Density (g/cm3)
Oxygen O2 Gas Colorless -218 -183 0.0014
Mercury Hg Liquid Silvery-white
-39 357 13.5
Bromine Br2 Liquid Red-brown -7 59 3.12
Water H2O Liquid Colorless 0 100 1.00
Sodium Chloride
NaCl Solid White 801 1413 2.17
Example: Physical Properties
States of Matter
Solid fixed shape and volume,
incompressibleLiquid
fixed volume, takes the shape of its container
Gastakes the volume and shape of
its container
STATES of matter
Bromine
Gas (Vapor)
Liquid
Change of Phase
Condensation gas liquidFreezing liquid solidDeposition gas solid
Melting solid liquidEvaporation liquid gasSublimation solid gas
Boiling: Evaporation occurring beneath the liquid’s surface.
BONUS REGENTS QUESTION
Which physical change is endothermic?
(1) CO2(s) → CO2(g)
(2) CO2(g) → CO2(ℓ)
(3) CO2(ℓ) → CO2(s)
(4) CO2(g) → CO2(s)
Chemical Properties and Chemical Changes
Is changing phase a physical or chemical change? ___________________Explain:
H2O composition is fixed- compound
Gaseous Phase Liquid Phase
REGENTS QUESTION
Coal is a fuel consisting primarily of carbon. In an open system, the carbon that burns completely in air produces carbon dioxide and heat. This reaction is represented by the balanced equation below.
C(s) + O2(g) → CO2(g)+ heat
Draw at least five particles to represent the phase of the product.
Chemical Properties
The ability of a substance to transform into a new substance (to undergo a chemical change).
Example: Magnesium reacts with oxygen to form magnesium
oxide.
Magnesium Mg
Burning of Magnesium2Mg+ O2 2MgO
REGENTS QUESTION
Which term identifies a type of chemical reaction?
(1) decomposition
(2) sublimation
(3) Distillation
(4) vaporization
Physical ChangesPhysical change: a change in the
physical properties of a substance.
Composition does not change.
May be reversible or irreversible.Examples:
Reversible: Liquid water < -- > solid water
Irreversible: Tearing a piece of paper
Chemical Change
A change that produces matter with a different composition than the original matter.
Atoms rearrange themselves into new combinations.
Burning of MethaneCH4 +2O2 CO2 + 2H2O
Burning of MethaneCH4 + 2O2 CO2 + 2H2O
Recognizing a Chemical Change
energy exchange production of a gascolor changeformation of a precipitate
Formation of a Precipitate
Cu(OH)2
Precipitate
The Law of Conservation of Mass (Antoine Lavoisier)
In any chemical or physical change, mass is neither created or destroyed
Mass is CONSTANT
Classification of Matter(by composition)
(Pure) Substance
Matter that has a uniform and definite composition.Elements: organized on a
periodic table, unique name, one, two or three letter symbol
Compounds: two or more elements combined chemically
REGENTS QUESTION
All atoms of uranium have the same
(1) mass number
(2) atomic number
(3) number of neutrons plus protons
(4) number of neutrons plus electrons
REGENTS QUESTION
Which substance can not be broken down by a chemical change?
(1) ethane
(2) silicon
(3) Propanone
(4) water
c) Elements and Compounds
Pure substances
Elements can NOT be decomposed by chemical means, but compounds can.
ElementsThe simplest substances.Can not be separated into simpler
substances.Building blocks of all matter. More than 100 known elements.Represented by chemical
symbols.
Chemical Symbols of Elements
System started by Jons Berzelius (Sweden, 1779-1848)
One or two first letters of name of the element.
Many elements names have roots from: Latin, Greek, mythology, geography, names of scientists.
Examples:
Americium, Am
Einsteinium, Es
Bromine, Br
Helium, He
Lead(Plumbum), Pb
Niobium, Nb
Iron (Ferrum), Fe
Mendelevium, Md
CompoundA substance that contains two or more
elements chemically combined.
Compounds have different properties from the individual substances.
(Ex: H2O)
Example: H2O
The law of definite proportions states that a compound is always composed of the same elements in the same proportions.
Percent composition
Substance or mixture?
If composition is fixed and may not changesubstance
REGENTS QUESTION
Which sample of matter is a mixture?
(1) Br2(ℓ)
(2) KBr(s)
(3) K(s)
(4) KBr(aq)
Mixture: a physical blend of two or more substances that are not chemically combined.
Homogeneous:
Uniform composition and properties throughout
Heterogeneous two or more sustances are physically combined and retain their original properties
MixturesA physical blend of two or more
substances.
Mixtures
Homogeneous
Heterogeneous
Example: Stainless Steel
A homogeneous mixture of:
-Iron (Fe)
-Chromium (Cr)
-Nickel (Ni)
Heterogeneous Mixtures
Non-uniform composition throughout the mixture
Two or more phases.
Example:
Oil and vinegar
Example: Gaseous MixtureElements argon and nitrogen and
a compound (water vapor). Choice ?
Note:
Mixtures can be physically separated.
Mixtures exhibit physical properties similar to the components of the mixture.
Separation Methods
Use differences in the physical properties of the components of the mixture.
Example: Separate iron filings from sulfur using a magnet.
Filtration: separates a solid from a liquid in a heterogeneous mixture
Distillation: -separate dissolved solids from a liquid -uses boiling and condensation.
Distillation of Crude Oil (Refining)
Crude Oil is a mixture of Hydrocarbons
BONUS REGENTS QUESTION
Which formula represents a hydrocarbon?
(1) CH3I
(2) CH3CH3
(3) CH3NH2
(4) CH3OH
Distillation of Crude Oil
REGENTS QUESTION A mixture consists of sand and an aqueous
salt solution. Which procedure can be used to separate the sand, salt, and water from each other?
(1) Evaporate the water, then filter out the salt. (2) Evaporate the water, then filter out the sand.
(3) Filter out the salt, then evaporate the water. (4) Filter out the sand, then evaporate the water.