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 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