Chapter 1 1.12.11 - Classifying Matter NO Pure Substances...

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Unformatted text preview: Classifying Matter NO Pure Substances All Matter Can it be separated by a physical process? YES Mixtures NO Elements Can it be broken down into simpler ones by chemical means? YES Compounds 1.6 Physical and Chemical Properties and Changes Physical Properties – characteristics of a substance that can be observed without changing the substance into another substance. Some physical properties n n n n n n n Color Odor Taste Hardness Density melting/boiling temperature magnetic properties Physical and Chemical Properties and Changes Chemical Properties – characteristics of a substance that can be observed when the substance undergoes a change in its composition. n Electricity + water (H2O) → H2 gas and O2 gas. Iron (Fe) + oxygen (O2) → rust (Fe2O3) n Physical and Chemical Properties and Changes Chemical Change – a change that alters the composition of the substance. n n Combustion of wood in a forest fire Digestion of food in the stomach Note: products have different physical properties than the original substance. Classifying Matter Matter: anything that occupies space and has mass Pure Substance: n n n n only one kind of matter cannot be physically broken down into different components. Includes elements and compounds On the particle level, all particles are the same Classifying Matter Elements: n n n Contain only one kind of atom cannot be broken down into simpler substances by any physical or chemical means listed in the periodic table Classifying Matter Compounds: n n combination of two or more elements in fixed proportions represented by the chemical formula CO2 Carbon dioxide 1C, 2O CO carbon monoxide 1C, 1O n Can be separated into their individual elements chemically, but not physically Classifying Matter Mixture: n n n n physical combination of two or more substances may be present in variable amounts can be separated by physical means On the particle level, there are different kinds of particles Classifying Matter Homogeneous Mixture: n n n n Substances are evenly distributed at the particle level A sample taken from one part of the mixture is identical to that taken from any other part Example: salt dissolved in water Example: components of gasoline Heterogeneous Mixture: n n Composition of the mixture varies from one region to another Example: Salt mixed with sugar Classifying Matter Sugar (C6H12O22) Salt (NaCl) Diamond nickel lemonade sulfur dioxide Salt water Pond water US nickel Grou p The Periodic Table Period The Periodic Table Abundances of Elements The Periodic Table Abundances of Elements The Periodic Table The Periodic Table n n n n An orderly arrangement of all elements Order (numbering) relates to the subatomic particles making up each atom of the element Elements in the same Group (column) behave similarly Eg. The Periodic Table Naturally occurring forms of elements n n n Solids – most elements Liquids – Hg (mercury) and Br2 (Bromine) only Gases All Group 8A (He, Ne, Ar, Kr, Xe, Rn) Also H2, O2, N2, F2, Cl2 n Note: these are ELEMENTS only, COMPOUNDS may also be solid liquid or gas The Periodic Table Other classifications n n n Metals – shiny, conduct electricity; left side of periodic table Non-metals – varied appearance, don’t conduct well; right side of periodic table Metalloids – somewhere in between periodic table disposal of sodium Atoms and Molecules Types of pure substances n n Element – 1 kind of atom Compound – 2 or more kinds of atoms Individual Particles n n Atom – the smallest unit of an element that can exist Molecule – a particle made up of more than one atom May have atoms of the same element (ELEMENT) May have atoms of different elements (COMPOUND) A space filling model for a water molecule, H2O Oxygen atom A molecule is a fixed number of atoms held together by chemical bonds in a certain spatial arrangement. The chemical formula represents the type and number of each element present. Two hydrogen atoms 1.7 Atoms and Molecules n n n Atom of the Element Iron Fe ● Atom of the Element Copper Cu ● Atom of the Element Oxygen O ● Molecule of the Element Oxygen O2 ●-● Molecule of the Element Fluorine F2 ●-● Molecule of the Compound Carbon MonoxideCO ●-○ Molecule of the Compound Water H2O ●-○-● Molecule of the Compound Sulfur Dioxide SO2 ●-○-● n n n n n Atoms and Molecules Chemical Formulas n n represents the composition of a substance Tells how many and what kind of atoms SO2 - 1 sulfur atom, 2 oxygen atoms F2 - 2 fluorine atoms H2O - 2 hydrogen atoms, 1 oxygen atom Atoms and Molecules Chemical Symbol Ozone Helium Carbon tetrachloride Nitrogen dioxide Lead Carbon fullerine O3 He CCl4 NO2 Pb C60 Type/# of atoms Atom or Molecule Element or Compound Atoms and Molecules Chemical Symbol Ozone Helium Carbon tetrachloride Nitrogen dioxide Lead Carbon fullerine O3 He CCl4 NO2 Pb C60 Type/# of atoms 3O 1 He 1C, 4Cl 1N, 2O 1 Pb 60 C Atom or Molecule Element or Compound Atoms and Molecules Chemical Symbol Ozone Helium Carbon tetrachloride Nitrogen dioxide Lead Carbon fullerine O3 He CCl4 NO2 Pb C60 Type/# of atoms 3O 1 He 1C, 4Cl 1N, 2O 1 Pb 60 C Atom or Molecule molecule atom molecule molecule atom molecule Element or Compound Atoms and Molecules Chemical Symbol Ozone Helium Carbon tetrachloride Nitrogen dioxide Lead Carbon fullerine O3 He CCl4 NO2 Pb C60 Type/# of atoms 3O 1 He 1C, 4Cl 1N, 2O 1 Pb 60 C Atom or Molecule molecule atom molecule molecule atom molecule Element or Compound element element Compound compound element element Chemical Formulas and Names Elements - names given in the periodic table n n n n n Fe – Iron He – Helium O2 – Oxygen N2 – Nitrogen Exception: common names O3 – technically oxygen; commonly ozone Chemical Formulas and Names Compounds – use the chemical formula and naming rules Naming Rules n n Rule 1: More metallic (further left) element comes first (same order as formula) Rule 2: 2nd element gets modified to end in –ide Mg Cl2 - Magnesium and Chlorine – Magnesium Chloride Chemical Formulas and Names Elements Correct Formula (assume only one of each atom in the molecule) Name Br and Na O and Ba H and Cl Ca and O Chemical Formulas and Names Elements Correct Formula (assume only one of each atom in the molecule) NaBr BaO HCl CaO Name Br and Na O and Ba H and Cl Ca and O Chemical Formulas and Names Elements Correct Formula (assume only one of each atom in the molecule) NaBr BaO HCl CaO Name Br and Na O and Ba H and Cl Ca and O Sodium Bromide Barium Oxide Hydrogen Chloride Calcium Oxide Chemical Formulas and Names Problem: some atoms can combine in more than one set of proportions law of multiple proportions: if elements combine in two or more different proportion, then each combination is a different compound with different properties. n Example: Nitrogen and oxygen can react to form many different combinations Chemical Formulas and Names Naming Rules n Rule 3: if there is more than one of an element in the formula, it is modified with a prefix to indicate how many Chemical Formulas and Names NO2 SO2 N2O4 CO Chemical Formulas and Names NO2 SO2 N2O4 CO Nitrogen Dioxide Sulfur Dioxide Dinitrogen Tetroxide Carbon Monoxide Chemical Formulas and Names Note: n n if there is only one of the first element in the formula, the “mono” prefix is omitted if only one possible combinations of these elements exists the prefixes can be neglected Ex. MgCl2, there is no MgCl or MgCl3 Composition of Air: Major Components Nitrogen Oxygen Argon Carbon Dioxide Water N2 O2 Ar CO2 H2O 78% 21% .9% .04% 0-5% Composition of Air: Major Components Properties: N2 n n Inert, non-reactive at low temperatures Not nutritional very reactive, most useful for life breathed – reacts with food to release energy burning rusting and other corrosion O2 n n n n Composition of Air: Major Components Properties: Ar n inert – doesn’t react with much by-product of metabolism used by plants in photosynthesis produced when fossil fuels or wood or plastics burn in air CO2 n n n Units of Concentration for Major Components % composition n n n 78 g N2 per 100 g air? NO 78 molecules N2 per 100 molecules air? YES 78 L N2 per 100 L air? YES Units of Concentration for Major Components % composition by volume Units of Concentration for Major Components % composition by volume n n Doesn’t have to be whole numbers Ex. 45L sample containing 2.5L of CO2 Units of Concentration for Major Components % composition by number of particles Composition of Air: Minor Components Criteria Air Pollutants – 6 air pollutants for which the EPA has set permissible limits n n n n n n CO (gas) O3 (gas) – ground level ozone NO2 or NOX (gas) SO2 or SOX (gas) Pb (suspended small particles) Particulate Matter (PM) (suspended small particles) PM10 – average diameter of 10 x 10-6 m (10 micrometers) or less PM2.5 – average diameter of 2.5 micrometers or less Composition of Air: Minor Components CO n n Shape is similar to oxygen Prevents O2 from binding to hemoglobin suffocation attacks respiratory tissue triggers asthma, reduced lung capacity, increased susceptibility to respiratory illness interferes with plants’ ability to store food – more vulnerable to stressors reduces crop yields O3 n n n n Composition of Air: Minor Components NOX n n n n n n forms acid aerosols damaging to respiratory tissue respiratory illness and heart disease acid rain involved in ground level O3 production reduced visibility other toxins can form, some causing biological mutation SOX n acid aerosols, same as above except O3 production Composition of Air: Minor Components Lead n n n n damages kidneys, liver, brain, nerves, other organs seizures, mental retardation, behavioral disorders, memory problems osteoporosis and reproductive disorders high blood pressure and heart disease Particulate Matter n n aggravates and causes respiratory problems visibility reduced Taking and Assessing Risks Risk Assessment - evaluating scientific data and making predictions in an organized manner about the probabilities of an occurrence Taking and Assessing Risks Activities Associated with Air Pollution: n Energy production (gasoline, coal, methane burning) transportation manufacturing and large-scale agriculture energy for home/industry pollutants cause respiratory and pulmonary damage and death damage to environment (acidification of water, damage to forests, etc) Benefits n n n Risks n n Taking and Assessing Risks Risk Assessment Toxicity n the intrinsic hazard of a substance (somewhat hard to measure) Exposure n n the amount of a substance encountered Exposure to air pollutants depends on: exposure time lung size and breathing rate concentration of pollutants in air Taking and Assessing Risks Human Studies n follow a population long-term, keeping track of risk factors and incidence of disease animals given controlled doses Bacteria cultures given controlled doses Animal Studies n Bacteria Studies n Taking and Assessing Risks Pollutant CO O3 Primary Standards 9ppm 35 ppm .08 ppm .12 ppm NOx SOx Pb PM10 PM2.5 .053 ppm .03 ppm .14 ppm 1.5 μg/m3 50 μg/m3 150 μg/m3 15.0 μg/m3 Averaging Times 2nd highest 8-hour average 2nd highest 1-hour average 3 year average of 4th highest 8-hour average 2nd highest 1-hour average Annual average Annual average 2nd highest 24-hour average Quarterly average Annual Average 2nd highest 24-hour average Annual average Concentration – ppm and ppb Parts per million (ppm) n 9ppm CO = 9 parts CO out of 1,000,000 parts total 30ppb SO2 = 30 parts SO2 out of 1,000,000,000 parts total 1 μg/m3 = 1x10-6 g/m3 = .000001 g/m3 Parts per billion (ppb) n μg/m3 n Concentration – ppm and ppb Converting from % to ppm to ppb Concentration – ppm and ppb 1.7ppm = 5% = .00007% = .0275% = 5ppm = .3ppm = Concentration – ppm and ppb 1.7ppm = 5% = .00007% = .0275% = 5ppm = .3ppm = .00017% 1700ppb 50,000ppm 50,000,000ppb .7ppm 700ppb 275ppm 275,000ppb .0005% 5000ppb .00003% 300ppb Concentration – ppm and ppb How much pollution do you breathe? n Average breath = .5 L/breath n n CO @ 4.6ppm: Concentration – ppm and ppb n O3 @ .17ppm: .17 O 3 × 1.34 x 10 22 air molecules = 2.28 x 10 15 1,000,000 total air n SOx @ .042ppm: .042 SO x × 1.34 x 10 22 air molecules = 5.63 x 10 14 1,000,000 total air n n NOx @ .040ppm: similar to above O2 @ 21%: Chemical Changes – Balancing Reactions Ira Remsen Reaction Cu(s) + 4 HNO3 (aq) —> Cu(NO3)2 (aq) + 2 H2O (l) + 2 NO2 (g) Chemical Changes – Balancing Reactions Balancing Reactions n n n Reactants → Products Sulfur + oxygen → sulfur dioxide S + O2 → SO2 Chemical Changes – Balancing Reactions Dalton’s Atomic Theory n n n n All matter is made up of tiny indivisible particles called atoms Atoms cannot be created, destroyed or transformed into other atoms in a chemical reaction All atoms of a given element are identical Atoms combine in simple, whole-number ratios to form compounds Chemical Changes – Balancing Reactions Conservation of matter and mass: the number and type of atoms is the same on both sides of a reaction equation, even if they are now in different combinations Chemical Changes – Balancing Reactions Rules for Balancing Reactions n n Write the correct chemical formulas of reactants and products in equation form Add numbers in front of the various species until all are balanced Combustion of Hydrocarbons Combustion – a particular type of reaction in which a substance is combined with oxygen (O2) n n n S + O2 → SO2 C + O2 → CO2 2N + O2 → 2NO Hydrocarbons: compounds made of mostly hydrogen and carbon n n n n n CH4 - methane C2H6 – ethane C3H8 – propane C4H10 – butane C8H18 – octane Combustion of Hydrocarbons Types of Combustion Reactions n n n Complete: Hydrocarbon + O2 → CO2 + H2O Incomplete: Hydrocarbon + O2 → CO + H2O Very Incomplete: Hydrocarbon + O2 → C + H2O Balancing Combustion Reactions n n write correct formulas of reactants and products balance in the order of C, H, O Air Pollutants: Direct Sources SOX n Main Source: Coal fired electrical power plants (67%) Solid sulfur in coal burns to form gaseous SOX n How can it be reduced? low sulfur coal technology to remove sulfur from coal or SOX from power plant exhaust reducing energy use n Progress so far 1985: 20 million tons of SO2 from coal burning in U.S. 2005: 15 million tons of SO2 from coal burning in U.S. Air Pollutants: Direct Sources CO n Main Source: incomplete combustion of hydrocarbons Motor vehicle exhaust 56% Non-road engines/vehicles 22% n How can it be reduced? better engine design computerized control of fuel/air ratio Catalytic converters CO→CO2 oxygenated fuels smaller cars/hybrids reduced use – better use of mass transit and carpools n Progress so far Twice as many cars on the road as 25 years ago 2001 ambient CO level 62% lower than 1982 level Air Pollutants: Direct Sources Pb (Lead) n Main Sources: metal processing (57%) Waste disposal (16%) USED TO BE from leaded gasoline, but not anymore n How can it be reduced? Unleaded gasoline is already in use technology to reduce emissions by lead smelters and battery manufacturers correct disposal of batteries n Progress so far 1999: lead emissions from vehicles in U.S. down 95% from 1990 levels Leaded gasoline not yet banned in all countries. Air Pollutants: Direct Sources NOX n Main Sources: Combustion of N2 in car engines (49%) Combustion of N2 in electrical utilities (27%) Note: not directly produced by gasoline or coal n How can it be reduced? catalytic converters also convert NO back to N2 and O2 and reduce VOCs more efficient car (boat, plane, etc) engines smaller cars/hybrids reduced use – better use of mass transit and carpools reduced electricity use n Progress so far NOX levels have increased ~9% since 1980, but have begun to decrease in the past few years. Air Pollutants: Indirect Sources Secondary pollutant – produced from reactions between two or more pollutants; not emitted directly Ground Level Ozone (O3) n n Main Source: reactions between NOX and VOCs Note: Not directly emitted by cars or power plants, but related to pollutants that are NOx – already discussed sources VOCs n n n gasoline fumes escaping when gas is pumped household solvents unburned gasoline from tailpipe NOx + VOCs + heat + sunlight → Ozone Air Pollutants: Indirect Sources n How can it be reduced Reduce NOx levels Reduce use of solvents Don’t pump gas/drive/mow on hot days Air Pollutants Particulate Matter n Main Sources: a variety of human activities motor vehicles Factories construction sites Farms some natural sources – volcanoes, forest fires n How can it be reduced? control emissions from industrial sources by cleaner technology. more efficient and cleaner diesel engines some really can’t be controlled well ...
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This note was uploaded on 04/11/2011 for the course CHEM 102 taught by Professor Henshaw during the Winter '11 term at Grand Valley State University.

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