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Chapter 2“Matter and Change”p. 38
Describing MatterProperties:
1) Extensive – depends on amt of matter in sample
- ex’s. mass, volume, calories, magnetism
2) Intensive – depends on type of matter, not amt.
- Hardness, Density, B.P.- All samples of same substance have
same intensive prop’s. (same composition)
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Identifying SubstancesPhysical Properties- observed & measured w/o changing composition◦color, hardness, m.p., b.p.
Chemical Properties- observed by changing comp of material ◦ability to burn, decompose, ferment, react w/, etc.
States of matter1) Solid- cannot flow (definite
shape & volume)2) Liquid- definite vol - takes shape
of container (flows)3) Gas- w/o definite vol or shape &
flows◦ Vapor- gaseous but normally liquid or solid @
room temp water “gas”, or water “vapor”?
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Three Main Phases – page 41
States of Matter
Solid
Liquid
Gas
Definite Volume?
YES
YES
NO
Definite Shape?
YES
NO
NO
Result of aTemperature Increase?
Small Expans.
Small Expans.
Large Expans.
Will it Compress?
Not easily
YES
Not easily
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4th state: Plasma - formed at hi temps; ionized phase of matter (Sun)
Solid Liquid Gas
Melt Evaporate
CondenseFreeze
Sublime
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Physical vs. Chemical ChangePhysical change changes visible appearance w/o changing comp of material◦Boil, melt, cut, bend, split, crack◦Is boiled water still water?
Reversible, or irreversibleChemical change - change where new substance formed◦Rust, burn, decompose, ferment
Section 2.2 Mixturesp. 44
Mixture - physical blend of 2+ components
1) Heterogeneous – uniform in comp• Choc chip cookie, gravel, soil
2) Homogeneous - same comp thruout(solutions)
• Kool-aid, air, salt water Every part keeps own prop’s
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Solutions - homogeneous mixtures
Mixed molecule by molecule, so too small to see diff pts
occurs btwn any state of matter: gas-gas; liquid-gas; gas-liquid; solid-liquid; solid-solid (alloys)◦Steel (Fe, Cr & Ni)
Phase?
“phase” describes any pt of sample w/ uniform comp of properties
A homogeneous mixture consists of a single phase
A heterogeneous mixture consists of two or more phases.
Note Figure 2.6, page 45
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Separating MixturesSome by physical means: rocks & marbles, iron filings & sulfur (magnet)
Differences in physical props used to separate mixtures
Filtration - separates solid from liquid in hetero mix. (by size) –Figure 2.7, page 46
Separation of a MixtureDistillation: takes advantage of different boiling pts.
NaCl boils at 1415 oCH2O boils at 100 oCMg boils at 1107 oC
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Separation of a MixtureComponents of dyes such as ink may be separated by paper chromatography.
Chromatography video
Forensic Ink Analysis
Applications of Chromatography 2 Greek words: ◦ chroma "color" and “graphein "to write"
Biological labs: ◦ ID amino acids ◦ detects drugs in urine
Environmental labs: ◦ ID contaminants in waste oil ◦ pesticides in groundwater ◦ test drinking water & test air quality
Pharmaceutical companies ◦ prepare quantities of extremely pure materials.
Food industry ◦ ID contaminants like aflatoxin naturally occurring toxin produced by fungus
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Sec 2.3 Elements & Compounds p. 48
Substances are either:a) elements, orb) compounds
Pure Substances
Element Compound
Simplest matter
1 type of atom
Cannot be broken down
Broken down by
chemical methods
different prop’s thanelements
2+ atomschemicallycombined
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Compounds v.s. MixturesMixtures
Made of more thanone kind of material
Made by a physical change
Variablecomposition
Compounds
Made of one kindof material
Made by a chemical change
Definitecomposition
Which is it?
ElementCompoundMixture
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Chemical Change
1+ substances are converted into different substances.
Heat & lightoften indicate chem chg
A “chemical change” chg producing matter w/ diff. comp than original matter
Classification of Matter
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Symbols & Formulas
118 elements 1 - 2 letter symbol 1st letter CAP; 2nd
letter lowercase ◦ B, Ba, C, Ca
Some names Latin◦ Table 2.2, page 52
cmpds have formula◦ H2O, NaCl, C12H22O11
Chemical Changes
Chemical property - ability of substance to undergo specific chem change •Fe + O = rust•rusting - chem prop of Fe
During chem chge comp of matter always changes
Sec 2.4 Chemical Rxns p. 53
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Chemical Rxns are…When 1+ substances changed into new substances
Reactants- start w/Products- end w/Products have NEW PROPS diff from reactants
Arrow points from reactants tonew products
Recognizing Chemical Changes1) Energy absorbed/released (temp
changes hotter/colder)2) Color changes3) Gas production (bubbling, fizzing, or
odor change; smoke)4) precipitate forms - solid separates
from solution (won’t dissolve)5) Irreversibility - not easily reversedSome ex’s not chem – boiling water
bubbles, choc syrup in milk, etc.