Substance = a chemical (element or mixture) Substance mixture chemical process = chemical reaction (new substances result) physical process = same substances present through out Physical or chemical processes? Process Corresponding Physical or Chemical Property bread rising through the use of baking soda carbonates decompose to form CO 2 boiling water apples rotting biomolecules such as carbohydrates can be digested (often oxidized) by microorganisms burning coal carbon burns in oxygen freezing liquid freezing point distilling a liquid boiling/condensation point evaporating a liquid vapor pressure exploding dynamite undergoes a disproportionation reaction decomposes titration of an acid with a base acid-base neutralization filtration of a solid from a liquid particle size (molecules versus small macroscopic particles) condensation of water formation of polyethylene from ethylene baking of a potato nitroglycerin exploding high pressure gas cylinder exploding iron rusting crushing of stone tarnishing of silver melting lead Popcorn popping flint and steel producing sparks smoke scattering light water condensing on metal metal getting hot addition across double bond thermal decomposition of biomolecules denaturation of proteins vaporization of water undergoes a disproportionation reaction decomposes tendency of gas to expand reactivity of iron with oxygen hardness, lack of malleability reactivity of silver with oxygen melting point
Physical vs. chemical property? Property Physical or chemical? Intensive or Extensive? color density reaction with oxygen tendency of metal to corrode solubility of sugar in water density soluble (dissolves) in water metal can tarnish or corrode mass melting point Intensive property Does not depend on size of sample (property of material making up sample) Same of all samples Can be used to identify the sample (qualitative analysis = what is it?) Extensive property Depends on size of sample property of specific sample being studied Varies with sample size Can be used to determine how much is present (Qualitative Analysis how much is there? or How concentrated is it?)
Sample Substance vs. Mixture Homogenous vs. Heterogenous gasohol (gasoline with alcohol added) gasoline solid butter snickers bar grape juice apple juice apple cider orange juice tomato juice uncooked hamburger cooked hamburger freshly brewed coffee vinegar slice of white bread whipped cream wedding ring sweat Nile River Water Concho River Water human blood air compressed air in a scuba tank table salt sand copper nitrogen gas argon gas carbon dioxide gas mineral water brass (a Zn/Cu alloy) sucrose (table sugar) HCl O 2 O 3 beer I 2 Ce ClF S 8 filtered water chicken noodle soup element vs. compound
trail mix snack fruit salad cool aid drink (already mixed) cool aid mix (in packet) sand and water alcohol dissolved in water damp air clouds Properties of a sample of 24 carat gold (classify them) a. 2.976 g b. doe not tarnish c. density = 19 g/ml d. insoluble in water e. has a yellowish color f. is shiny and reflects light (has luster) g. is malleable (can be deformed without breaking) Properties of a sample of rose gold (18 carat) (classify them) an alloy a. 5.61 g b. doe not tarnish c. density = 12.7 g/ml d. insoluble in water e. has a pink color f. is shiny and reflects light (has luster) g. is malleable (can be deformed without breaking) h. 75% gold, 21% copper and 4% silver Properties of sodium (Na) a. density is greater than kerosene and less than water b. lower melting point than most metals c. excellent conductor of heat and electricity d. soft (can be cut with a knife) e. freshly cut sodium is shiny, but rapidly tarnishes in air f. it reacts vigorously with water to form H 2 and NaOH Properties of H 2 a. At room temperature, less dense than any other gas
b. reacts vigorously with water c. Liquefied below -253 o C d. Gas does not conduct electricity Properties of formaldehyde (CH 2 O) a. characteristic acrid smell b. soluble in water c. burns in air d. gas at room temperature e. colorless Properties of silver a. tarnishes over time b. tarnished silver can be polished to a shiny metallic shine (luster) c. reacts with chlorine to produce a white solid d. It sinks in water Give three properties that you can use to distinguish between... a. salt, copper, sand b. sugar, water, oxygen