Describing Matter Properties: 1)Extensive 1)Extensive – depends on amt of matter in sample - ex’s. mass, volume, calories, magnetism 2)Intensive 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”?
States of Matter Solid Liquid Gas Definite Volume? YES NO Definite Shape? YES NO Result of a Temperature Increase? Small Expans. Large Expans. Will it Compress? Not easily YES Not easily
4 th state: Plasma - formed at hi temps; ionized phase of matter (Sun)
Solid Liquid Gas Melt Evaporate Condense Freeze Sublime
Physical vs. Chemical Change Physical 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 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 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. Chromatography video Forensic Ink Analysis
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
PureSubstances Element Simplest matter 1 type of atom Cannot be broken down Compound Broken down by chemical methods different prop’s than elements 2+ atoms chemically combined
Compounds v.s. Mixtures Mixtures Made of more than one kind of material Made by a physical change Variable composition Compounds Made of one kind of material Made by a chemical change Definite composition
Symbols & Formulas 118 elements 1 - 2 letter symbol 1 st letter CAP; 2 nd letter lowercase ◦B, Ba, C, Ca Some names Latin ◦Table 2.2, page 52 cmpds have formula ◦H 2 O, NaCl, C 12 H 22 O 11
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 Sec 2.4 Chemical Rxns p. 53
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)…. ◦ CO 2 & H 2 O vapor Law of conservation of mass
- Page 55 reactants = product 43.43 g Original mass = 43.43 g Final mass