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