unit 5: matter and energy i. classification of matter
TRANSCRIPT
Unit 5:
Matter and Energy
I. Classification of Matter
P u re S ub s tan ces M ix tu res
M a tte r
Classification of Matter
E le m e n ts C o m p o un ds
P u re S ub s tan ces
A llo ys S o lu tio ns
H o m o ge n eo us
C o llo id s S u spe n sio ns
H e te ro ge n so us
M ix tu res
M a tte r
Pure Substances
A “pure substance” is one that has the same composition throughout
All parts of this substance has the same properties, regardless of shape, size, or state
Examples:
watersilversodium chloridenitrogenheliumsucrose
B.Mixtures
Mixtures are physical combinations of more than one compound and/or element
These are 2 or more distinct substances
May have varying propertiesproperties throughout
Two major categories of mixtures:
1) Heterogeneous
2) Homogeneous
Mixtures
Heterogeneous Mixtures = those that are not the same throughout;
vary in composition; can see the separate
partsExamples: sand &
water, ???
Homogeneous Mixtures =
those that look the same throughout, but can still be separated physically
Examples: 14kt gold, sugar water, ???
C. Properties of Matter
Physical Property
those that can be observed without changing the identity or composition
Ex] density, solubility, phase, etc.
Chemical Property
describes how a substance reacts; composition changes
Ex] flammability, oxidation, etc.
Intensive vs. Extensive Properties
Extensive Properties depend upon the depend upon the amountamount presentMass, shape, volume, etc.
Intensive Properties remain the same remain the same regardlessregardless of amountDensity, boiling point, solubility, etc.
Website reference
http://www.chem1.com/acad/webtext/pre/matter.html
D. Physical and Chemical Changes
Physical changes are generally are reversible
The substance may look differently, but has the same intensive properties
D. Chemical Changes
Chemical changes generally alter the composition of the substance
End product has different properties
Sample is destroyed
II. Particle Diagrams of Matter [drawings of types and phases]
Identify the type of substance and the phase in each diagram below.
Draw a particle diagram of nitrogen gas and iodine.
III. Separation Techniques
These methods separate mixtures that are physically combined
End result, or products, are the compounds or elements that composed the mixture
Four major methods: A) Filtration C) EvaporationB) Distillation D) Chromatography
A. Filtration
Filtration is used to separate a solid from a liquid or a solution; starts with suspension
Materials: filter paper, funnel, collection beaker
Advantages: easy, common, fast, recovers all parts
Disadvantages: inaccurate, difficult with small particles, depends on technique, human error common
B. Distillation
This is a method of separating components of a liquid mixture based on different boiling points
Materials: boiling flask, collection flask, condenser, water, heat source
Advantages: recovers all parts, collects pure substances, separate complex mixtures
Disadvantages: costly equipment, slow, can be difficult
Evaporation is the removal of a solvent by evaporating it, leaving behind the solute
Materials: Evaporating dish, heat sourceAdvantages: easy, common, usually fastDisadvantages: lose solvent, solute may
be contaminated, inaccurate, can be difficult
C. Evaporation
D. Chromatography
This uses solubility rules and mass to separate components of a complex solution
Materials: stationary phase [paper], mobile phase [solution], sample
Advantages: very accurate, rater fast, can separate hundreds of components
Disadvantages: expensive, must have the proper solvent, destroys sample
Several different types: paper, gas, or liquid
IV. Laws of Matter and Energy
A. Law of Conservation of Energy
B. Law of Conservation of Matter
C. Law of Constant Composition
ExceptionException: : nuclear reactions
V. Energy
C h e m ica l N u c le a r
P o ten tia l
H e a t E le c trica l M e cha n ica l T h e rm a l E le c tro m ag n e tic
K in e tic
E n e rgy
B. Changes in Energy
Endothermic
a reaction or change that
ABSORBS
heat energy
Exothermic
a reaction or change that RELEASES
heat energy
C. Temperature vs. Heat
Temperature = the average kinetic energy of the particles within an area
Heat = energy transferred between two objects of different temperatures
Heat moves from hotter object to the colder one
V. Heat Transfer and Calculations
Specific Heat (C)The amount of heat energy lost/gained by a
specific mass of a substance over a certain temperature change
The larger the value of specific heat, the more energy it takes to heat the object, oror the longer time it takes for the object to cool
Specific Heat
substances with LOW specific heats:MetalsAlloysSubstances w/ high
thermal conductivity
substances with LOW specific heats:glassSome PolymerswaterAir, inert gasesSubstances w/ low
thermal conductivity
B. Heat Equation and Calculations
q = m • C • Δ T
q= heat [J or kJ]
C = specific heat [J/gC]Δ T = change in temperature = Tf - Ti