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Chemistry
The study of the composition,
structure & properties of materials &the changes they undergo.
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6 Branches of Chemistry
Analytical: composition, separation &identification of materials.
Quantitative - measurements
Qualitative - describe w/outmeasurements
Organic: C comps. Inorganic: everything other than C
comps.
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6 Branches of Chemistry-cont.
Physical: physical props of materials
& rxn mechanisms
Biochemistry: materials & processes
in living things
Nuclear: subatomic particles &nuclear rxns
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Scientific Method
1) Observing
State the facts; dont infer
2)Hypothesizing
Classify, categorize
Temporary explanation
3) Theorizing
Repeatedly tested
model
4) Testing Validate, modify or discard theory
5) Law
Summarizes broad spectrum of experiments &
observations
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Matter- anything th takes up space & has mass
Substance - a particular kind of matterw/ a constantcomposition:
Elements & compounds Element - simplest form of matter; 1 kind of atom
118 natural 26 man-made
Metals
> 80; left side of P-table
Good conductors, sonorous, lustrous, high melting pts
Malleable: hammer into shapes
Ductile: draw into wires
Nonmetals
~ 20; right side of table
Good insulators; 11 gases; low melting pts.
Brittle solids
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The type and
the arrangement of particlesdetermines the properties
of the chemical.
Melting Point Boiling Point
Density Color
Malleability Conductivity
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Matter- cont.
Compounds- composed ofmore than 1 kind of atomjoined together chemically; always in definite ratios
Mixtures - a blend of 2 or more substances ea of
wh retains its own identity Homogeneous (solutions) : uniform throughout; 1
phase
Heterogeneous: more than 1 phase with definite
boundaries
Immiscible mixtures : 2 liquids
Suspensions : a liquid & solid
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Evidence of Particles
Diffusion - spontaneous spreading of
particles until evenly distributed
[HIGH] -> [LOW]
Brownian Motion - random motion of
particles due to their bombardment by
molecular particles
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States of Matter- properties relate to kinetics
Solids Definite shape & volume
Particles in fixed, tight pattern
Strong attractive forces
Particles vibrate in place
Liquids
Definite volume: take shape of container
Particles move: slide or flow
Weaker attractive forces
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States of Matter- cont.
Gases
Take shape & volume of containerParticles are rapidly moving
Almost no attractive forces
> 99.9% empty space!!!
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Solid, Liquid & Gases
& Plasma
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Bose-Einstein Condensate
What is temperature anyway??? Measurement of average kinetic energy of a system!
Hot = high KE = fast moving particles
Cold = low KE = slow moving particles
Absolute Zero (Kelvin vs Celsius) 0C = 273 K
Absolute Zero = 0 K
Quantum Blob Particles are fuzzy and begin to overlap quantum
mechanics
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Changes of State -cont.
Sublimation -
Solid -> gas
i.e. dry ice, iodine, snow Deposition -
Gas -> solid
Melting & Boiling Pts Characteristic for a sub
Indicate purity
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Kelvin Temp Scale
Provides a direct measure of the average
kinetic E
K = Celsius + 273
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Chem vs. Physical Change
Physical change - state changes; cutting,
pounding, pulling, dissolving
** no new subs. formed
Chemical change - sub undergoes a change:
1 or more new subs form w/ diff characteristics
Signs of a chemical change:
1. 1 or more new subs. 2. E taken in or given off:
Exothermic - E released
Endothermic - E taken in
3. Not easily reversible
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Exo: Outside
A reaction in which energy is released
Gets HOT or
give off LIGHT
Examples:
Burning wood,
Bomb (non-nuclear)
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Endo: within
Reaction where energy is absorbed
Gets COLD
Example:
Ice Packs (NH4NO3)
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Chemical Reactions
Reactants -> (change to or yield)Products
Activation energy - min. amt. of E tostart a chemical rxn
Catalyst - a chem sub th speeds up arxn w/out being consumed
Decreases activation E
Often a transition metal
Place over arrow in an equation
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Energy needed to start a reaction
Match starts with a spark,
but a piece of paper needs a match and a
wooden log start with burning paper.Therefore, each
activation energy
is different.
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Collision Theory
The more successful collisions
(right E & orientation),
the more products produced!
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Law of Conservation of Matter &
Energy Neither matter of E is created in a chemical
rxn, but rather it is transformed.
E can be heat, light, electrical, kinetic, etc.
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Separating Mixtures
Separating Solids fr Liquids - forsuspensions
Filtering
Centifuging
Evaporating the solvent
Crystallizing - evaporate some solvent & cool;
solute will ppt. out
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Separating Mixtures -cont.
Separating a Mix of 2 Solids:
Dissolve 1
Filter suspension
Evaporate
Separate solvent fr soln:
Simple distillation - heat to boiling &
evaporate; solid left behind; collectcondensation
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Separating Mixtures -cont.
Separating 2 Liquids:
Separating funnel - for immisciblemixtures
Separates into layers based on density
Tap off different layers
Fractional distillation - for miscible
mixturesHeat to boiling pt. of 1 sub; evaporate &
condense
i.e crude oil
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Separating Mixtures -cont.
Separating a mixture ofColoredSubs:
Paper chromatography
Mixture = mobile phase wh is allowed to
pass over a stationary phase
Polarity separates:
Slowest moving = more attraction forstationary phase
Fastest moving = least attraction
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Solutions (homo mixtures)
2 parts to a solution: Solute - in lesser amount
Solvent - in greater amount
Universal Solvent - water!
Unsaturated - a soln th is able to dissolve more
solute
Saturated - added soluted will not dissolve
^ temp = ^ amount of dissolving Supersaturated - contains more solute than a sat
soln can normally hold
Very unstable- tends to precipitate (ppt) excess solute
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Solubility
Depends on temp.
Solubility - max. amt of a sub th will
dissolve in 100g of water at a specified temp ** varies widely for diff subs.
For solids: generally solubility ^ w/ ^ temp
Calculating Solubility - expressed as --g/100g of water at --- temp.
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Solubility - cont.
Solubility Curves
Graph of solubility (g/100 gH2O) vs.
Temp
Find solubility at various temps
Solubility of Gases (in liquids)
*** Solubility decreases w/ increasingtemp
Thermal pollution
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Other Solvents
Alcohol, acetone, gasoline, trichlorethane, etc.
Volatile - evaporate easily at room temp
** flammable & toxic
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