Presentation on theme: "Unit 1: Water: Exploring Solutions"— Presentation transcript:
1Unit 1: Water: Exploring Solutions Miss ShueyChem Comm
2Essential Questions What techniques can we use to purify water? What are the physical properties of water?Why do some substances readily dissolve in water and others do not?How does chemistry contribute to effective water treatment?
3Article reviewFish Kill Triggers Riverwood Water Emergency
4Section A: Sources and uses of water _________________________
5A.4 water supply and demand Family of four uses 390 gallons daily.Direct water use – volume that can be directly measured.Indirect water use – hidden uses of water that you may never have considered.Ex. Slice of pizza??Figure 1.12
6A5. water use in the usFor each region in the US, name the greatest single use of water.A. the east b. the south c. the midwestD. the west e. alaska f. hawaiiExplain the differences in how water is used in the east and the west. Think about where most people live and where most of the nation’s factories and farms are located. What other regional factors help explain the general patterns of water use?List two factors about the weather, economy, or culture that could explain the greatest water use within each of these six U.S. regions.
7a.6 where is the world’s water? 97% of the world’s water.OceanGlaciers
8Physical states of water Gaseous state: water vaporLiquid state: lakes, rivers, oceans, clouds, and rain.Solid state: ice
9City waterSurface water: water supply originated in a river or other body of water.Ground water: water in a well.
10Rural waterAquifer: water-bearing layer of rock, sand, or gravel, then pumped to the surface.
12Scientific MethodHypothesis – testable statement controls – remain constant variable – is changed Model – explanation of how phenomena occur and how data or events are related. Theory – broad generalization that explains a body of facts or phenomena.
13Accuracy and Precision Accuracy – close to the expected valuePrecision – a number of measurements close to each other.
14What is more accurate? Graduated cylinder Or Beaker
15Significant Figures Indicates how precise a measurement is. rule example1. Zeros between other nonzero digits are significant50.3 m has three sig figsB s has five sig figs2. Zeros in front of nonzero digits are not significant.0.892 kg has three sig figsms has one sig fig3. Zeros that are at the end of a number and also to the right of the decimal are significant57.00 g has four sig figsB kg has seven sig figs4. Zeros at the end of a number but to the left of a decimal are significant if they have been measured or are the first estimated digit; if not they are NOT significant.1000 m may contain from one to four sig figs, depending on the precision of the measurement, in this book it will be assumed there is one sig fig.20 m has one sig fig (scientific notation will indicated sig fig number)
16Rules for calculating with sig figs Type of calculationRuleexampleAddition or subtractionWhen measurements are added or subtracted, the answer can contain no more decimal places than the least accurate measurement97.3Round offMultiplication or divisionThe final answer has the same number of sig figs as the measurement having the smallest number of sig figs.123x 658
17Sig fig practicePerform these calculations following the rules for sig figs.26 x = ?15.3 / = ?= ?= ?
18SI unit – measurements in science SI unit – measurements in science. Volume Density – m/v A sample of aluminum metal has a mass of 8.4g. The volume of the sample is 3.1 cm3. calculate the density of aluminum.
21Dimensional analysis – math technique that allows you to use units to solve problems involving measurements.
22Section b Article reading B.1 PHYSICAL PROPERTIES OF WATER Matter – anything that occupies space and has mass.Physical properties: observed and measured without changing the substance.Density – mass of material within a given volume.D = m/v
23Water properties Freezing point – 0 C when liquid water forms a solid. Aqueous solution – water-based solution.Important aqueous solutions in your life:____________________
24b.3 mixtures and solutions Mixture – when two or more substances combine and retain their individual properties.Heterogeneous (suspension)Homogeneous (solution)SoluteSolventPg.30
25b.4 Particulate view of water Particulate level – at the level of its atoms and molecules.Atoms – building blocks of matter.Element – matter made up of only one type of atom.Compound – composed of the atoms of two or more elements bonded together in fixed proportions.Ex.
26Chemical formulas – representing compounds or elements, showing ratios of how they bond. Ex.Substance – element or compound with uniform and definite compositions.Molecule – smallest unit of a molecular compound that retains the properties of that substance.
27b.5 pictures in the mindMacroscopic – large-scale, easily observed without microscopes or other tools.Models – representations of atoms and molecules.Pg.33 ques. 1-7
28b.6 symbols, formulas, and equations Chemical symbols – letters to represent element.Periodic table of the elements – arrangement of elements according to the number of protons.
29Common elementsAluminum Al Hydrogen H Bromine Br Iodine I Calcium Ca Iron Fe Carbon C Lead Pb Chlorine Cl Magnesium Mg Cobalt Co Mercury Hg Copper Cu Nickel Ni Fluorine F Nitrogen N Gold Au Oxygen O Phosphorus P Potassium K Silver Ag Sodium Na Sulfur S Tin Sn
58b.8 Electrical nature of matter Electrons – negatively charged particlesProtons – positively charged particles, in nucleusNeutrons – neutral particles, in nucleus
59b.9 ions and ionic compounds Ions – electrically charged atoms or groups of atoms.Ionic compounds – substances composed of positive and negative ionsCation – positive ion Na+Anion – negative ion Cl-Polyatomic ion – ion consisting of a group of bonded atoms
60b.11 water testing Precipitate – insoluble material in water. Qualitative test – looking at non numerical descriptions.Quantitative tests – numerical data.
62b.12 pure and impure water Pg. 45 Gases in atmosphere dissolve in water, nitrogen, oxygen, carbon dioxide46-47 Read
63Sec. c investigating the cause of the fish kill Solubility – substance that will dissolve in water.Saturated – maximum quantity of a substance that will dissolve in a quantity of water.What effects solubility?
64Solubility curve – relationship between temperature and solubility
65Unsaturated solution – solution that contains less dissolved solute than the amount that the solvent can normally hold at that temperature.Supersaturated solution – unstable solution that contains more solute than could usually be dissolved at that temperature.Ex. Rock candy (pg.55)
66c.4 dissolving ionic compounds Form ions in waterPolar molecule – electrons are not evenly distributed throughout its structure.Partial positive region and partial negative region.Ex. water
68Diatomics Reactant and Products are shown in chemical equations Reactant are the substances that are used to make a chemical reaction Products are substances produced by the reaction Na + Cl ---> NaCl reactant --> productsDiatomic Molecules - some elements bond to themselves, like H2GEN-U-INE diatomic molecules U should remember that the diatomic molecules all end in -GEN or -INE(or H N F O I C B ) H2 N2 F2 O2 I2 Cl2 Br2
69c.8 inappropriate heavy-metal ion concentrations? Essential Metal Ions:Iron(II) Fe2+Potassium K+Calcium Ca2+Magnesium Mg2+Heavy-metal ions – atoms have greater masses than those of essential metallic elements, harmful to humans and other organisms.Lead Pb2+ -bind to proteins in biological systems,Hg2+ prevents proteins from performing theirnormal task.
70Heavy metal harmDamage to the nervous system, brain, kidneys, and liver, which can even led to death.They become concentrated within the bodies of fish and shellfish.Costly to removeHard to detectPrevention: using alternate materials in industry. Called Green Chemistry
71Lead Ions (Pb2+) Latin name – plumbum Plumber – water pipes in ancient Rome were commonly made of lead.Used in:Pottery, automobile electrical storage batteries, solder, cooking vessels, pesticides, and paintsMany were replaced with iron, copper or plastic materials.1970s lead was added to gas to produce a better-burning automobile fuel. Released in atmosphere.
72Mercury Ions Hg2+ Liquid at room temp Latin name = hydrargyrum, quicksilver or liquid silverUses:Electrical conductor, thermometers, thermostats, hats, light bulbs, pesticidesVapor is hazardous, absorbed through skin
74C.9 inappropriate ph levels pH – measure and report the acidic, basic, or chemically neutral character of a solution.Range =Neutral = 77> acidic7<basic (alkaline solutions)1pH unit = tenfold difference in acidity or alkalinitypH 3 soft drinks, pH 2 lemon juiceLemon juice is 10 time more acidic than soft drinks.
75Litmus paper Indicator to show level of acidity or alkalinity. Blue – basicRed – acidicAcidic and basic solutions conduct electricity.What does this tell you?Ions present in the solution.Acids – release H+ ionsBases – release OH- ions
76Neutral substances Sucrose, sodium chloride solutions = neutral Low pH in streamsFish-egg development is impairedIncrease the concentrations of metal ions by leaching metal ions from surrounding soil.High pH in streamsalkaline solutions are able to dissolve organic materials, including skin and scales
77EPA requirements Drinking water be within the pH range of 6.5 – 8.5 Fish can tolerate 5.0 – 9.0Did the pH change to kill all the fish?
78C.10 inappropriate molecular substance concentrations Molecular substances – composed of molecules not ions.Molecular substances can be harmful for aquatic life.Examples: ethanol C2H5OH, succinic acid C4H6O4, carbon dioxide CO2, oxygen gas O2What determines the solubility of a molecular substance in water?Distribution of electrical charge within molecules.Electronegativity – ability of an element’s atoms to attract shared electrons when bonding within a compound. causes e- to be unevenly distributed among the atoms.
79Polar molecule Negative and positive side of a molecule. “like dissolves like”Polar dissolves polarNonpolar dissolves nonpolarEx. Oils, soaps soap attracts oils
80c.11 solventsSoluble – will dissolveInsoluble – will not dissolve
81c.12 inappropriate dissolved oxygen levels? As temperature goes up less oxygen is dissolved.Gas solubility in water is directly proportional to the pressure of that gaseous substance on the liquid.Increase in water temperature affects fish by decreasing the amount of dissolved oxygen in the water and by increasing the oxygen consumption of fish.