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Chapter 2Chapter 2““MatterMatter and Change” and Change”p. 38p. 38
Describing MatterDescribing MatterProperties:Properties:
1)1) ExtensiveExtensive – depends on amt of matter in sample
- ex’s. mass, volume, calories, magnetism
2)2) IntensiveIntensive – depends on type of matter, not amt.
- Hardness, Density, B.P.- All samples of same substance have
same intensive prop’s. (same composition)
Identifying SubstancesIdentifying 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 matterStates 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”?
Three Main Phases – page 41Three Main Phases – page 41
States of MatterStates of Matter
Solid
Liquid
Gas
Definite Volume?
YES
YES
NO
Definite Shape?
YES
NO
NO
Result of a Temperature Increase?
Small Expans.
Small Expans.
Large Expans.
Will it Compress?
Not easily
YES
Not easily
44thth state: state: PlasmaPlasma - - formed at hi formed at hi temps; ionized phase of matter temps; ionized phase of matter (Sun)(Sun)
Solid Liquid Gas
Melt Evaporate
CondenseFreeze
Sublime
Physical vs. Chemical Physical vs. Chemical ChangeChange
Physical 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 changeChemical change - change where new substance formed◦Rust, burn, decompose, ferment
Section 2.2 MixturesSection 2.2 Mixturesp. 44p. 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
Solutions - homogeneous mixturesSolutions - homogeneous mixturesMixed 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?
“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
Separating MixturesSeparating 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 MixtureSeparation of a MixtureDistillation: takes advantage of different boiling pts.
NaCl boils at 1415 oCH2O boils at 100 oCMg boils at 1107 oC
Separation of a MixtureSeparation of a MixtureComponents of dyes such as ink may be separated by paper chromatography.
Chromatography video
Forensic Ink Analysis
Applications of ChromatographyApplications of Chromatography2 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
Sec 2.3 Elements & Sec 2.3 Elements & Compounds p. 48Compounds p. 48
Substances are either:a) elements, orb) compounds
Pure Pure SubstancesSubstances
Element Compound
Simplest matter
1 type of atom
Cannot be broken down
Broken down by
chemical methods
different prop’s than
elements
2+ atomschemicallycombined
Compounds v.s. MixturesCompounds v.s. Mixtures
MixturesMixtures
Made of more thanone kind of material
Made by a physical change
Variablecomposition
CompoundsCompounds
Made of one kindof material
Made by a chemical change
Definitecomposition
Which is it?Which is it?
ElementCompoundMixture
Chemical ChangeChemical Change
1+ substances are converted into different substances.
Heat & light often indicate chem chg
A “chemical change” chg producing matter w/ diff. comp than original matter
Classification of MatterClassification of Matter
Symbols & Symbols & FormulasFormulas
118 elements1 - 2 letter symbol1st letter CAP; 2nd
letter lowercase ◦B, Ba, C, Ca
Some names Latin◦Table 2.2, page 52
cmpds have formula◦H2O, NaCl, C12H22O11
Chemical ChangesChemical 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. 53Sec 2.4 Chemical Rxns p. 53
Chemical Rxns are…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 to new products
Recognizing Chemical ChangesRecognizing 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.
Conservation of Mass Conservation of Mass During any chem rxn, product mass = reactant mass
All mass accounted for:◦Burning wood results in products that appear to have less mass (ashes)….
◦CO2 & H2O vaporLaw of conservation of mass
- Page 55
reactants = product
43.43 g Original mass = 43.43 g Final mass