Chapter 2 “Matter and Change”

p. 38

Describing Matter Properties: 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)

Identifying Substances

  Physical Properties composition - observed & measured w/o changing ◦color, hardness, m.p., b.p.

Chemical Properties - observed by changing comp of material ◦ability to burn, decompose, ferment, react w/, etc.

States of matter

1) Solid - cannot flow (definite shape & volume) 2) 3) ◦  Liquid - definite vol - takes shape of container (flows) 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 41

States of Matter

Definite Volume?

Definite Shape?

Result of a Temperature Increase?

Will it Compress?

Solid YES YES Small Expans.

Not easily

Liquid YES NO Small Expans.

Not easily

Gas NO NO Large Expans.

YES

4

th

state: Plasma formed at hi temps; ionized phase of matter (Sun)

Freeze Melt

Sublime

Condense Evaporate

Solid Liquid Gas

Physical vs. Chemical Change

  

Physical change

appearance w/o changing comp of material ◦ changes visible Boil, melt, cut, bend, split, crack ◦ Is boiled water still water?

Reversible, or irreversible

Chemical change

new substance formed ◦ - change where Rust, burn, decompose, ferment

Section 2.2 Mixtures p. 44

 Mixture - physical blend of 2+ components 1) Heterogeneous • Choc chip cookie, gravel, soil 2) Homogeneous – uniform in comp - same comp thruout (solutions)  • Kool-aid, air, salt water Every part keeps own prop’s

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

Separating Mixtures

   Some 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 Mixture

Distillation:

takes advantage of different boiling pts.

NaCl boils at 1415 o C H 2 O boils at 100 o C Mg boils at 1107 o C

Separation of a Mixture

Components of dyes such as ink may be separated by

paper chromatography

.

Forensic Ink Analysis Chromatography video

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

Sec 2.3 Elements & Compounds p. 48

Substances

either: a) elements, or b) compounds are

Pure Substances Element Compound Simplest matter 1 type of atom Cannot be broken down Broken down by different prop’s than chemical elements methods 2+ atoms chemically combined

Compounds v.s. Mixtures Compounds Mixtures Made of one kind of material Made by a chemical change Definite composition Made of more than one kind of material Made by a physical change Variable composition

Which is it?

Chemical Change

A “chemical change” chg producing matter w/ diff. comp than original matter 1+ substances are converted into different substances.

Heat

&

light

often indicate chem chg

Classification of Matter

Symbols & Formulas

    

118

elements 1 - 2 letter symbol 1 letter lowercase ◦ st letter CAP; 2 B, Ba, C, Ca nd Some names Latin ◦ Table 2.2, page 52 cmpds have formula ◦ H 2 O, NaCl, C 12 H 22 O 11

Sec 2.4 Chemical Rxns p. 53

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



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 Changes 1) 2) 3) 4) 5) Energy

absorbed/released (temp changes hotter/colder)

Color Gas

changes production (bubbling, fizzing, or odor change; smoke) precipitate forms - solid separates from solution (won’t dissolve)

Irreversibility

- not easily reversed Some ex’s not chem – boiling water bubbles, choc syrup in milk, etc.

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)….

◦ CO 2 & H 2 O vapor

Law of conservation of mass

- Page 55

43.43 g Original mass = 43.43 g Final mass reactants = product