Presentation on theme: "What is Chemistry? The study of the composition, structure,"— Presentation transcript:
1What is Chemistry? The study of the composition, structure, & properties of substances and changesit undergo.A chemical is any substance that has a part in a chemical rxn or is produced.Practical UsesClothing – synthetic fabricNonstick cookware - TeflonPharmaceuticals - medications
2Categories of Science Concerned with living things Concerned with non i. Biological –ii. Physical -Concerned with nonliving things
3Branches of Chemistry Organic – Study of living - contains carbon. Inorganic – study of non-living – no carbon.Physical – study of properties, transformations,and interrelationship of energy and matter.
4Branches of ChemistryAnalytical – identification of substances & study ofcomposition of materialsBiochemistry – Process that occurs in living thingsconnects biological processes w/ chemical processes.Theoretical – the use of math & computers to understandthe principles behind observed chemical behaviorand to design and predict the properties of newcompounds.
5Matter & Its Properties Atom – the smallest particle of an element that retains the properties of that element.Elements – A substance that cannot be changed into a simpler substance under normal lab conditions
6Physical PropertiesProperties – characteristics enabling us to distinguish differences in matter.Physical properties – can be observed ormeasured w/o changing the identity of materialExtensive physical properties – depends on the amount ofmatter. (mass, length, volume).Intensive physical properties – does not depend on mass,melting pt, boiling pt, density, color, ductile,malleable, crystal shape, etc.
7Physical ChangeA physical change is the changing of a substance does not alter the chemical composition.It can change states.Cutting, grinding, expanding
8States of Matter Neither definite shape or volume SolidLiquidGasPlasmaDefinite shape & volumeDefinite volume, not shapeNeither definite shape or volumeGaseous system with ions
9Chemical Properties/Changes Alters chemical identification.Chemical reaction-Reactants -> ProductsReactants are the substances you start off withAnd they then react and yields a new product.Ex. Wood burning, matches, letting milk stand so itcan turn sour, iron rust, tarnishing silver.Na + Cl NaClCharcoal + O2 CO2Fe + O2 Fe2O3
11Classification of Matter Mixtures – retain own composition & properties.Heterogeneous – Not uniformHomogeneous – UniformPure substance – has a fixed composition. Are either compd. or elements.Elements – is on the periodic chart. (Simplest form)compounds – chemically combined ex. NaClEvery sample has exactly the same characteristic prop.Every sample has exactly the same composition.ex. H2O % H, % O
12DistillationMethod for physically separating a mixture of liquids or a solid dissolved in a liquid
13Matter & Energy a. Matter – Occupies space and has mass. Inertia – Resistance to change in motion.Weight Vs. Mass -Weight is the measure of gravitational pull.Mass is quantity of matter.Law of conservation of mass:Mass is neither created nor destroyed.
14Energy – Ability to do work or cause change Types of Energy -Kinetic Energy – in the form of motionPotential Energy – Stored energydepends on composition or positionLaw of Conservation of EnergyEnergy can change form, but it cannot beCreated nor destroyed under ordinary cond.
15Energy and changes in matter Exothermic – produce heat. Energy is released in the form of heat.H + O H2O + HeatEndothermic – gain heat. Energy,in a form of heat, is absorbed.Ex. Melting ice
16Periodic Table Families or Groups – Vertical columns, # 1 – 18 Periodic Table Families or Groups – Vertical columns, # 1 – Elements share properties.Periods – horizontal rowsMetals – Good conductors of heat & electricity.Shiny, luster, malleable, ductile, tensil.Non-Metals – Poor conductors of heat/electricity.Metalliods – Share characteristics of metals & nonmetals.SemiconductorsNoble Gases – unreactive gases.
17Symbols for elementsIUPAC – International Union of Pure & Applied ChemistryO – oxygen H –N - Na -Sb stibium – antimonyCu cuprum – copperAu Aurum – goldAg Argentum – silverNa Natrium – sodium
18Scientific method- logical approach to solutions of problems Parts –Observations – collecting dataQuantitative & QualitativeGeneralizing – Organize, analyze, & classifyHypothesis – testable statementTesting - experimentingTheory – Explains why things occur. Broad generalization thatexplains a body of facts or phenomena. ModelLaw – Describes a variety of scientific behavior
19Types of Data Qualitative – descriptive nonnumeric results Quantitative – gives definite, usually numeric, resultsNumberUnit
20Graphing Directly proportional Inversely proportional Types of Graphs: Title graphLabel axis – numbers & unitsChoose ScaleIndependent variable – X – axis (Usually Time)Dependent variable – Y – axisPlot PointsDraw Best Fit LineDirectly proportional Inversely proportionalDividing 1 by the other If product is constantgives a constant valueTypes of Graphs:Line graph Bar graph Pie/ circle graph
21Pie Graph Data Gender # of ppl Elderly 27 Women 13 Men 6 Children 15 To get percentages:Gender# of pplElderly27Women13Men6Children15Total61Get part / whole # X 10044.3 %Elderly: 27/61 X 100 =21.3 %9.8 %24.6 %WomenMenChildrenTotal100 %Degrees: = X159.5 °
22Units of Measurement-SI system Standards of MeasurementSI – International System of Units1. Based on units of ten, makes it easier to use2. Used world wideSI Base Units - (pg 34)Fundamental SI UnitsQty Symbol Unit name Unit abbreviationLength l Meter mMass m Kilogram kgVolume V Liter LTime t second sTemperature T kelvin KAmount of substance n mole mol
23SI Units Kilo hecto deka base deci centi milli King Henry Died by Drinking Chocolate MilkThere are 1000 base units in one kiloThere are 1000 milli in one base unit
24Derived SI Units D = 10.8 g 4.0 cm3 D = 2.7 g/cm3 D = m/v Density = Mass/volumeVolume = l X w X hFind the density of a piece of aluminum w/ avolume of 4.0 cm3 and a mass of 10.8 g.D = 10.8 g4.0 cm3D = 2.7 g/cm3D = m/v
25Derived Units Density D = 453.3 g 123.0 ml What is the density of a block of marble with amass of g and a Volume of ml?D = mvD = g123.0 mlD = 3.685g/ml
26Accuracy Vs. PrecisionACCURACY – Refers to the agreement of a particular value with the true value.PRECISION – Refers to the degree ofagreement among several elementsof the same quantity.
29Percent ErrorAccepted value - Experimental valuePercent error =accepted value.X 100What is the percent error for a mass measurement of 17.7 g, given that the correct value is 21.2 g?% error = g g21.2 g16.5 % errorX 100 =
30Significant Figures All digits known plus one final digit Measurements from equipment
31Counting Significant Figures All non-zero numbers are significantZeros* Leading zeros – never* Captive zeros – Always* Trailing zeros* With a decimal – count* Without a decimal – don’t count
323 Questions for Zeros Is there a number in front? Is it trapped? No – Not significantYes – May be… go to #2 & #3Is it trapped?Yes - It is significantIs there a Decimal?No – Not SignificantYes – It is significant
34Calculations – multiplication & Division * The answer is rounded off to the same number of significant figures as in the measurement with the fewest sig. Fig.13.0 ml* ml X ml =* g / 0.04 cm3 =62.560 g/cm3
35Calculations – Addition & Subtraction Results should be rounded off so that the final digit is in the same place as the number with the fewest digits.\213.67____55.08– =55.075. \311.67Rounding312.Less than 5 = stay the sameMore than 5 = increase oneIf 5 = if odd increase by oneif even leave it alone
36| | | Scientific Notation 4.6 X 10 –4 cm 2.4 X 10 -1 g 5.02 X 10 4 m Must be a number from 1 to 9 !!!!!!!!!|* g (2 significant figures)2.4 X g|* m (3 significant figures)5.02 X 10 4 m|* cm (2 significant figures)4.6 X 10 –4 cm
37SI - Prefixes Kilo, hecto, deka, Base, deci, centi, milli Grams, liters, metersKilo, hecto, deka, Base, deci, centi, milliKing Henry Dances barbarically down center maineKing Henry Died by drinking chocolate milk1.0 Kg = g1.0 hg = 100 g1.0 dag = 10 gGrams, liters, meters10 dg = 1.0 g100 cg = 1.0 g1 000 mg = 1.0 g
38Chemistry Dominoes Rules Don’t slam or throw dominoesTake turnsQuickly get quiet when I call for your attention.To End The GameThe player who makes the connection to the last domino winsCount up the number of dominoes left on the table. Each domino is 1 point.Award the winner the points left on the table.
39Game PlayEach payer draws 1 domino to see who plays first (high domino)Shuffle (wash) the dominoesEach player draws 5 dominoesPlayer 1 plays a number blank (if no number blank, draw) This is the starting dominoPlayer 2 plays a number blank. (if no number blank, draw) This is the end domino.For the rest of the game, players play dominoes that will cancel the top number on the dominoIf you can not play, draw 1 domino. This domino may be played.
40Factor Label ________|__________ Draw your T Write conversion-equivalent statements to…Cancel out unitsTop – Multiply, Bottom – DivideThe mass of a quarter is 10.4g, how manymilligrams is that?________|__________mg10.4g1000= mg| g1.0
41Factor Label km Express a distance of 28. Meters in centimeters and then in kilometers.28. mcm100= 2,800 cmm1.028. mkm1.0= km1000m
42Factor Label 3.2 X 10 7sec * 1.0 year = __________________ seconds 1.0 yr365 days= 31,536,000 sec24 hrs60 min60 sec1 yr1 hr1 min1 day3.2 X 10 7sec
43Factor Label Dimensional Analysis 1. How many kilograms are in grams?2. How many liters are in 13.4 kL?3. A pencil is 7.5 centimeters, how many millimeters?4. You want to order a bicycle with a 225 mm frame, but thesizes in the catalog are given only in inches, what shouldyou order?5. A student enters a 10.0 km run. How many yards is the run?
44Quiz 25.3 ft = _______________ mm 7.5 mg = ______________ hg 12.5 kl = _______________ ml5.4 X 10 –6 km= _________ mm3.0 L = ________________ cm325.0 weeks = ____________ sec
45Heat & Temperature Temperature – measure of average kinetic energy Heat – sum of kinetic energy in all of the particles in a sampleA tub of boiling water & a cup full of boiling water
47Heat TransferConvection – transfer of heat by the motion of particles in a fluidConduction – transfer of heat through matter by colliding particlesRadiation – transfer of energy in the form of electromagnetic wavesHeat always moves from high energy to low energy. (hot to cold)
48ExamplesHot air balloonsHot water and cold water mixingHeating a panBoiling water
49Units of Heat Joule Calorie 1.0 cal = 4.180 joules The SI unit of heat energy as well as allOther forms of energy.Calorimeter – measures the energy absorbed orreleased as heat in a chemical or physical change.1.0 cal = joules
50Heat CapacityAmount of heat energy needed to raise the temperature of a sample 1oC
51Specific Heat Q = m X Cp X DT Amount of heat energy needed to raise the temperature of 1g of a sample 1oC.EquationQ = m X Cp X DTUNITSJoules = JGrams = gJ/g* oCoCQ = energy lost/ gainedM = massCp = specific heatDT = delta T = change in temp.
52Problems 1oC to 41oC and was found to have absorbed . A 4.0 g sample of glass was heated from1oC to 41oC and was found to have absorbed32 J of heat. What is the specific heat ofthis type of glass?
53Problems 1oC to 41oC and was found to have absorbed . A 4.0 g sample of glass was heated from1oC to 41oC and was found to have absorbed32 J of heat. What is the specific heat ofthis type of glass?Q = m Cp DTm=4.0gDT=41oC-1oC=40oCQ=32JCp = 0.20J/goC
54problemHow much heat did the same glasssample gain when it was heated from41oC to 71oC?
55How much heat did the same glass sample gain when it was heated from problemHow much heat did the same glasssample gain when it was heated from41oC to 71oC?Q = m Cp DTQ=(4.0g)(0.20J/goC)(30oC)Q=24Jm=4.0gDT=71oC-41oC=30oCCp=0.20J/goC
56Quiz 4.5 m = __________ km 899.9 ml = ________ L .54 kg = __________cg 4.5 ml = __________cm3D = 2.45 g/ml, mass = 12.5 g vol. = ?Vol = 25.5 ml, mass = 32.3 g D = ?D = 3.4 g/cm3 vol = 1.5 cm mass = ?List the things that a graph must contain(at least 4 things)