Transcript Chapter 2 Matter and Change

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- 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 matter
1) 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 41
States of Matter
Definite Definite
Volume? Shape?
Solid
Liquid
Gas
YES
YES
NO
Result of a
Temperature Will it
Compress?
Increase?
YES
Small
Expans.
NO
Small
Expans.
NO
Large
Expans.
Not
easily
Not
easily
YES
4th state: Plasma - formed at hi
temps; ionized phase of matter
(Sun)
Sublime
Condense
Freeze
Melt
Solid
Evaporate
Liquid
Gas
Physical vs. Chemical Change
 Physical
change changes visible
appearance w/o changing comp of
material
◦ Boil, melt, cut, bend, split, crack
◦ Is boiled water still water?
 Reversible, or irreversible
 Chemical change - change where
new substance formed
◦ Rust, burn, decompose, ferment
Section 2.2 Mixtures
p. 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 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 oC
H2O boils at 100 oC
Mg boils at 1107 oC
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 are
either:
a) elements, or
b) compounds
Pure
Substances
Element
Simplest
matter
1 type
of atom
Compound
Cannot be
broken
down
Broken down
different
2+ atoms
by
prop’s than chemically
chemical
elements
combined
methods
Compounds v.s. Mixtures
Compounds
Mixtures
Made of one kind
of material
Made of more than
one kind of material
Made by a
chemical change
Made by a
physical change
Definite
composition
Variable
composition
Which is it?
Mixture
Element
Compound
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
 1st letter CAP; 2nd
letter lowercase

◦ B, Ba, C, Ca

Some names Latin
◦ Table 2.2, page 52

cmpds have formula
◦ H2O, NaCl, C12H22O11
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) Energy absorbed/released (temp
changes hotter/colder)
2) Color changes
3) Gas production (bubbling, fizzing, or
odor change; smoke)
4) precipitate forms - solid separates
from solution (won’t dissolve)
5) 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)….
◦ CO2 & H2O vapor
 Law of conservation
of mass
- Page 55
43.43 g Original mass = 43.43 g Final mass
reactants
=
product