Presentation on theme: "Unit 1 Introduction to Chemistry"— Presentation transcript:
1Unit 1 Introduction to Chemistry Internet web site:
2Material Safety Data Sheet (MSDS) --gives informationabout a chemical-- lists “Dos” and “Don’ts;”emergency procedures
3a one-time exposure that causes damage Chemical Exposureacute exposure vs. chronic exposurea one-time exposure that causes damagedamage occurs after repeated exposuree.g.reaction to drugsor medicatione.g.smoking,asbestos
4How Toxic is “Toxic?” Chemicals may cause harm in many different ways: FlammableExplosiveRadioactiveCorrosiveIrritantCarcinogenicMutagenicTeratogenic
5LD50the lethal dosage for 50% of the animals on which the chemical is testedThere are various ways an LD50 can be expressed. For example, acetone has the following LD50s:ORL-RAT LD50: 5,800 mg/kgIHL-RAT LD50: 50,100 mg/m3hSKN-RBT LD50: 20 g/kg
6LD50 Example Chemical A: LD50 = 3.2 mg/kg Chemical B: LD50 = 48 mg/kg Which is more toxic?Chemical A is more toxic because LESS is necessary to kill half of a given population
8The Functions of Science pure science applied sciencethe search forknowledge; factsusing knowledgein a practical waye.g., properties of aluminumstronglightweightgood conductor
9Corning Glass NASA’s Problem Design a material Corning Glass Company that is clear and can with-stand extreme differencesin temperature without fail-ing (cracking).Design a face shieldto protect and provideclear vision.Corning Glass CompanyFAILED…butSUCCEEDED at makinggreat cookware that canwithstand extremes in temperature.Often times in science, great discoveries are made serendipitously or by accident. People set out with a goal in mind and discover something else, quite remarkably.
10Aluminum Mining 1850s: aluminum sold for $500 / lb Charles Martin Hall 4-6 pounds bauxitecurrent1 lb Al+=1850s: aluminum sold for $500 / lbCharles Martin HallDeveloped method to extract aluminum from bauxiteHall’s methodAs a result, $0.30/lbCharles Martin Hall ( ) was motivated by a professor at Oberlin College who remarked that anyone discovering a cheap method of producing aluminum would become rich and famous. Hall's discovery, in his home laboratory within eight months of his graduation, was the foundation of the aluminum industry in the United States.Paul Heroult ( ) a student of LeChatelier's, was, like Hall, 23 years old when he discovered the same method of producing aluminum. Heroult's discovery was the foundation of the aluminum industry in Europe.Earth's crust is ~8.3% by mass of aluminum. This makes aluminum the third most abundant element and the most abundant metal. Aluminum metal was not isolated until 1825, when Hans Oersted produced it in a pure form. It was considered a semi-precious metal (rare and expensive) in 1884 when an aluminum cap was placed on the Washington monument.
11Science attempts to establish cause/effect relationships Science can NEVER prove a cause/effect relationship, only make a correlation…
12risk-benefit analysis weigh pros and cons before deciding Because there are many considerations for each case, “black/white thinking” rarely applies. It is usually shades of grey.
13How does scientific knowledge advance? 1. curiosity2. determination3. persistence4. good observations
15** Key: Be a good observer. observation inferenceuses the fivesensesinvolves a judgmentor an assumption
16Observations are also called data. Types of DataObservations are also called data.qualitative data quantitative data--descriptions--measurementse.g.,colorless liquide.g.,17 mL; 83oC(vs. clear liquid)
17Candle Observation Activity This cartoon is used the day after we perform the "Observations of a Burning Candle Lab" for a humorous set induction.
18A Description of a Burning Candle A photograph of a burning candle is shown1 in the upper right corner. The candle is cylindrical2 and has a diameter3 of about 3 cm. The length of the candle was initially about 16 centimeters4, and it changed slowly5 during observation, decreasing about 1 cm in one hour6. The candle is made of a translucent7, white8 solid9 which has a slight odor10 and no taste11. It is soft enough to be scratchedwith the fingernail12. There is a wick13 which extends from top to bottom14 of the candle along itscentral axis15 and protrudes about 5 mm above the top of the candle16. The wick is made ofthree strands of string braided together17.A candle is lit by holding a source of flame close to the wick for a few seconds. Thereafter thesource of flame can be removed and the flame sustains itself at the wick18. The burning candlemakes no sound19. While burning, the body of the candle remains cool to the touch20 except nearthe top. Within about 1.5 cm of the top the candle is warm21 (but not hot) and sufficiently softto mold easily22.The flame flickers in response to air currents23 and tends to become quite smoky while flickering24.In the absence of air currents, the flame is of the form shown in the photograph, though it retains some movement at all times25. The flame begins about 2 mm above the top of the candle26, and at itsbase the flame has a blue tint27. Immediately around the wick in a region about 2 mm wide and extending about 5 mm above the top of the wick28 the flame is dark29. This dark region is roughly conical in shape30. Around this zone and extending about 1 cm above the dark zone is aregion which emits yellow light31, bright but not blinding32. The flame has rather sharply definedsides33 but a ragged top34. The wick is white where it emerges from the candle35, but from the baseof the flame to the end of the wick36 it is black, appearing burnt, except for the last 0,5 cm, where it glows red37. The wick curls over about 3 mm from its end38. As the candle becomes shorter, the wick shortens too, so as to extend roughly a constant length above the top of the candle39. Heat is emittedby the flame40, enough so that it becomes uncomfortable in 10 to 20 seconds if one holds his finger10 cm to the side of the quiet flame41 or 10 – 12 cm above the flame42.Burning a Candle“Wax is a mixture of compounds containing chiefly carbon and hydrogen. When the wick is lit, some wax is drawn up the wick and vaporizes. The vapor burns, using oxygen in the air. The yellow part of the flame is caused by carbon particles incandescing (glowing) at high temperatures. Unburned carbon forms soot.”Eyewitness Science “Chemistry” , Dr. Ann Newmark, DK Publishing, Inc., 1993, pg 30
19Parts of the Scientific Method Identify an unknown.Make a hypothesis:a testable predictionRepeatedly experiment to testhypothesis.procedure: order of events inexperiment(i.e., a recipe of what was done)variable:any factor that couldinfluence the result
20A Scientific Experiment Experiments must be controlled:Only one variable can change at a timeIndependent variable:a variable you control and manipulate (x-axis)Dependent variable:the variable you measure as you change I.V. (y-axis)conclusion: must be supported with evidence from the data collected
22Scientific Method Make observation Ask question Develop hypothesis Test hypothesiswith anexperimentTest hypothesiswith furtherexperimentsRevisehypothesisAnalyze dataand drawconclusionsHypothesisISsupportedHypothesisis NOTsupportedDeveloptheoryWysession, Frank, Yancopoulos,Physical Science Concepts in Action, 2004, page 8
23Scientific Law vs. Scientific Theory states what happens, i.e., a relationship between various quantities--Laws are often written inthe form of… an equation.-- e.g.,Newton’s law of gravity,laws of conservation
24a scanning tunneling microscope (STM) theory:tries to explain WHY orHOW something happens--based on current evidence-- e.g.,Theory of Gravity,Atomic Theoryimages of nickel atomstaken by an STMa scanning tunneling microscope (STM)
25Phlogiston Theory of Burning 1. Flammable materials contain phlogiston2. During burning, phlogiston is releasedinto the air3. Burning stops when……object is out of phlogiston, or…the surrounding air containstoo much phlogiston.(superceded by combustion theory of burning)
26________________________________Dollars Rob L. Brown, Sr. or Mary H. Brown1007 Shady LaneNormal, IllinoisDate_________Pay to theOrder of$________________________________DollarsNATIONAL CITY BANK OF MICHIGAN/ILLINOISSPRINGFIELD, ILLINOISMemo________________ ___________________________: :Blank ChecksRob L. Brown, Sr.1437 Tampa Avenue, Apt. J-432Bloomington, IllinoisDate_________Pay to theOrder of$________________________________DollarsIllinois State BankCHICAGO , ILLINOISMemo________________ ___________________________: :
28The Greeks believed there were four elements The BeginningEarly practical chemistry:household goods, weapons,soap, wine, basic medicineThe Greeks believed therewere four elements~D___DD___earth wind fire water
29Allegedly, this substance would turn cheap metals into gold Alchemy(~500 – 1300 C.E.)the quest for the Philosopher’s Stone(the elixir, the Sorcerer’s Stone)Allegedly, this substance would turncheap metals into goldAlchemical symbols for substances…. . .. ..GOLDSILVERCOPPERIRONSAND
30changing one substance into another transmutation:changing one substanceinto anotherCOPPERGOLDPhilosopher’sStoneIn ordinary chemical reactions…we cannottransmute elements into different elements
31Alchemy was practiced in many regions of the world, including China and the Middle East.Alchemy arrived in western Europearound the year 500 C.E.Modern chemistry evolved from alchemy.
32Contributions of alchemists: experimental techniquesnew glasswareinformation about elementsdeveloped several alloys
33What is chemistry?the study of matterand its changes
34Areas of Chemistry organic biochemistry the study of carbon containing compoundsthe chemistry ofliving thingsinorganicphysicalstudies everythingexcept carbone.g., compoundscontaining metalsmeasuring physicalproperties ofsubstancese.g., the meltingpoint of gold
35Careers in Chemistry research (new products) production (quality control)development (manufacturing)chemical salessoftware engineeringteaching
36The skills you will develop by an earnest study of chemistry will help you in any career field.
37The Scope of Chemistry bulk chemical manufacturing acids, bases, fertilizers**sulfuric acid (H2SO4) = #1 chemicalpetroleum productsfuels, oils, greases, asphaltpharmaceuticals1 in 10,000 new drugsgets FDA approvalsynthetic fibersnylon, polyester, rayon,spandex
39Colloidal SilverUsed to treat fungal infections, skin rashes, Lyme disease, HIV/Aids and food poisoning
40OK SupplementsCalcium, Cranberry, Fish Oil, Vitamin D, Lactobacilius
41Chemistry impacts:everyoneall fields of endeavor
42Government Regulation of Chemicals The various levels of government regulatechemicals to protect the:environmentworkerEPAOSHAconsumerOSHA: Occupational Safety and Health Admin.CPSC: Consumer product safety commissionFDAUSDACPSC
45shows how many of something are in each category Bar Graphshows how many of something are in each category# of students
46shows how a whole is broken into parts Pie Graphshows how a whole is broken into partsPercentage ofWeekly Income
47shows continuous change Line Graphshows continuous changeStock Price over TimeIn chemistry…you will always use a line graph.
48Elements of a “good” line graph 1. title2. axes labeled, with units3. neat4. use the available space
49Graphing HWTimeTotal Dist. cycled (km)8 a.m.9 a.m.1210 a.m.2311 a.m.33noon421 p.m.502 p.m.573 p.m.634 p.m.68Distance Cycled (km)Time (h)Extrapolation: predicting a pattern outside of a data set using the graphInterpolation: estimating a data point within the set of data using the pattern of the graph
51Scientific Notation…used to express very large or very small numbers. Also used to maintain correct SF.Form: (# from 1 to 9.999) x 10exponent800 = 8 x 10 x 10= 8 x 1022531 = x 10 x 10 x 10= x 103== 1.4 x 10–3(-) exponent = number < 1(+) exponent = number > 1
52Put in standard form1.87 x 10–5 =3.7 x 108 = 370,000,0007.88 x 101 = 78.82.164 x 10–2 =Change to scientific notation12,340 = x 1040.369 = 3.69 x 10–10.008 = 8 x 10–31,000,000,000 = 1 x 1096.02 x 1023 =602,000,000,000,000,000,000,000
54The EE or EXP or E key means “times 10 to the…” How to type out 6.02 x 1023:How to type out 6.02 x 1023:6EE.326EE.32not…WRONG!6y x.32WRONG!or…x16.2EE3and not…TOO MUCH WORK.y x32x16.
55Also, know when to hit your (–) sign. (before the number,after the number,or either one)
561.2 x 1052.8 x 1019=1.2EE598Type this calculation in like this:–15Calculator gives…E–15or…This is NOT written…4.3–15But instead is written…4.3 x 10–15or4.3 E –15
577.5 x 10–6 (–8.7 x 10–14) =–6.5 x 10–194.35 x 106 (1.23 x 10–3) =5.35 x 103 or 53505.76 x 10– x 10–4 =5.84 x 10–138.8 x 1011 x 3.3 x 1011 =2.9 x 1023
58Accuracy and Precision All numerical data are the resultof uncertain measurements.precision: a measure of the degree offineness of a measurement; itdepends on the extent to which theinstrument is calibratede.g.,8 mvs mvs m
59When repeated, precise measurements yield similar answers each time. e.g., precise…0.653 m0.652 m0.654 mimprecise…0.7 m0.8 m0.6 mA good rule of thumb is…It is the % difference that is important.
60Three types of error can affect accuracy. how close a measuredvalue is to the true valueThree types of error can affect accuracy.human error:mistake in reading instrumentor recording results-- minimize with repeated measurementsmethod error:using measuring instrument improperlye.g., parallax in measuring with a meter stickinstrument error:measuring device isimproperly calibratede.g., bathroom scale that always reads 5 lbs. too heavy
61Significant Figuresabout…A student is combining separate water samples, all of differing volumes, into one large bucket. Samples A, B and C are 25.5 mL, mL and 51 mL, respectively. Once combined, what is the total volume of all the samples?92.87 mLNO!Because the samples were each measured with a different level of precision, we must factor that into our calculations by identifying what are called significant figures.
62Measurement and Precision The last digit of any measured number is assumed to be an estimate (uncertain)The second to last digit is assumed to be known with certaintyA (25.5 mL) B (16.37 mL) C (51 mL)(think dashes…)2660502516.416.3
63Identifying Significant Figures Counting SF in a numberNon-zero numbers: ALWAYS count as SFZeroesLeft: NEVER count as SF ( )Middle: ALWAYS count as SF (5001)Right: sometimes…w/ decimal point: count as SF (25.10)w/o decimal point: DO NOT count as SF (8200)Exact Numbers: IGNORE SF(assumed to have an infinite number of SF)Counts (28 students in this class)Constants (1 mol = x 1023)Conversions (1 in = 2.54 cm)Relative to the non-zero numbers
64How many Sig Figs? Measurement Number of SF Measurement Number of SF 2 0.030 kgx 106 mg6 x 104 secg20.06 cm1.050 m271540.12 kgcmkg6.00 x 106 kg409 cmdmg271354Now, determine the # of SF in Part A and B of the Sci. Not. HW (5 min)
65Sig Figs with Calculations Note: For any calculations, always perform the entire calculation without rounding, and then round the final answer.Addition/SubtractionRound the answer to the LEAST number of decimal places found (least precise)=Multiplication/DivisionRound the answer to the smallest number of SF found5.282 x 3.42 =→ rounded to 48.7→ rounded to 18.1(3.42 only has 3 SF)
66Back to the original question… A student is combining separate water samples, all of differing volumes, into one large bucket. Samples A, B and C are 25.5 mL, mL and 51 mL, respectively. Once combined, what is the total volume of all the samples?25.5 mL mL + 51 mL = mL93 mLCould I write that as 93.0?NO!
67Round to the correct number of significant figures. Calculator says… 2 sig. figs.3 sig. figs.5 sig. figs.75.638760042008.4845E-47675.675.6000.530.528390,000388,000* x 1054,200* 4.20 x 103x 1038.5 x 10–48.48 x 10–4x 10–4* = requires scientific notation
68Units must be carried into the answer, unless they cancel.5.2 kg (2.9 m)(18 s)(1.3 s)=kg*ms20.644.8 g (23 s)(18 s)(37 s)=gs0.17
69x + y = z x + y = z – y – y x = z – y Solve for x. x and y are connected by addition. Separate them using subtraction. In general, use opposing functions to separate things.x + y = z– y– yThe +y and –y cancel on the left,x = z – yleaving us with…
70Numerical Example x – 24 = 13 x – 24 = 13 +24 +24 x = 37 Solve for x. x and 24 are connected by subtraction. Separate them using the opposite function: addition.x – 24 = 13+24+24The –24 and +24 cancel on the left,leaving us with…x = 37
71( ) F = k x __ 1 k F = k x (or) F = k x k x = F k __ Solve for x. x and k are connected by multiplication. Separate them using the opposite function: division.(or)F = k xkThe two k’s cancel on the right,leaving us with…x =Fk__
72( ) Numerical Example 8 = 7 x __ 1 7 8 = 7 x (or) 8 = 7 x 7 x = 8 7 __ Solve for x.8 = 7 x()__178 = 7 xx and 7 are connected by multiplication. Separate them using the opposite function: division.(or)8 = 7 x7The two 7’s cancel on the right,leaving us with…x =87__
73( ) ___ x BA = TR H BAH = xTR 1 TR ___ BAH = xTR ___ BAH TR x = Solve for x.___xBA=TRHOne way to solve this is to cross-multiply.BAH = xTR1TR()___Then, divide both sides by TR.BAH = xTR___BAHTRx =The answer is…
77How many cm are in 1.32 meters? equality:1 m = 100 cm(or 0.01 m = 1 cm)conversion factors:______1 m100 cm______1 m100 cmor1.32 m1 m100 cm= cmWe use the idea of unit cancellationto decide upon which one of the twoconversion factors we choose.
78Again, the units must cancel. How many m is 8.72 cm?equality:1 m = 100 cmconversion factors:______1 m100 cm______1 m100 cmor8.72 cm1 m100 cm= mAgain, the units must cancel.
79How many kilometers is 15,000 decimeters? 15,000 dm10 dm1 m1,000 m1 km1.5 km=
80How many seconds is 4.38 days? ____()()_____()____24 h1 d1 h60 min1 min60 s4.38 d= 378,432 sIf we are accounting for significant figures, we would change this to…3.78 x 105 s
814. Convert 41.2 cm2 to mm2 Recall that… 1 cm = 10 mm ( )2 ( )2 ( )2( )241.2 cm21 cm2102 mm2=4,120 mm2
82SI-US Conversion Factors Equality Conversion FactorsLength2.54 cm1 in1 in2.54 cm2.54 cm = 1 in.and39.4 in1 m1 m39.4 in.1 m = 39.4 in.andVolume946 mL1 qt1 qt946 mL946 mL = 1 qtand1.06 qt1 L1 L1.06 qtandDominoes Activity1 L = 1.06 qtMass453.6 g1 lb1 lb453.6 g453.6 g = 1 lband2.20 lb1 kg1 kg2.20 lb1 kg = 2.20 lband
84( ) ( ) ______ ______ Find area of rectangle. A = L . W 4.6 cm = (4.6 cm)(9.1 cm)9.1 cm= 42cm2. cmcm.cm()______100 cm1 mConvert to m2.42 cm22= m2()______1 cm10 mmConvert to mm2.42 cm22= mm2
85For the rectangular solid: Length = 14.2 cmWidth = 8.6 cmHeight = 21.5 cmFind volume.V = L . W . H= (14.2 cm)(8.6 cm)(21.5 cm)=2600cm3
86( ) ______ Convert to mm3. 1 cm 10 mm 2600 cm3 3 = 2,600,000 mm3 = x 106 mm3mm and cm differ by a factor of……….mm2 “ cm2 “ “ “ “ “ ……….mm3 “ cm3 “ “ “ “ “ ……….101001000
87Density how tightly packed the particles are m V D Density = Typical units:g/cm3 for solidsg/mL for fluidsGlass: liquid or solid?liquidsand gases
88To find volume, use…1.a formulaV = p ∙ r2 ∙ hV = l ∙ w ∙ h2.water displacementV = ?VfinalVinitialVobject = Vfinal – Vinitial
89Things that are “less dense” float in things that are “more dense.” ** Density of water =1.0 g/mL = 1.0 g/cm3Things that are “less dense” floatin things that are “more dense.”(And things that are “more dense” sinkin things that are “less dense.”D < 1 g/cm3D > 1 g/cm3D < 1 g/cm3D < 1 g/cm3The density of a liquid or solid is nearly constant,no matter what the sample’s temperatureDensity of gases is highly dependent on temperature
90Ironwood TreesSeveral different varieties of hardwood trees, having densities between 1.34 and 1.49 g/cm3Most dense species is South African Ironwood (black ironwood)Olea laurifoliaFound in Florida andWest IndiesD = 1.49 g/cm3
91Will Bowling Balls sink or float in H2O? If DBB > 1, it will sinkIf DBB < 1, it will float21.6 cm in diameterVsphere = 4/3 p r3V = 4/3 p (10.8 cm)3mVDV = 5,276.7 cm3m = D Vm = (1.00 g/cm3)( cm3)m = gSince the mass of a BB varies, let’s figure out at what mass it will sink v. float…or 11.6 lbs
92Density Calculations1. A sample of lead (Pb) has mass22.70 g and volume cm3. Find sample’s density.mVD=2. Another sample of lead occupies 16.2 cm3of space. Find sample’s mass.Vm = D V= 184g
93Indiana Jones DensityWatch the famous opening scene to Indiana Jones and the Raiders of the Lost ArkThe “pure gold” idol has a density of 19.3 g/cm3. How much would it mass?Indy replaces the idol with a bag of sand (density = 2.5 g/cm3). Why did he activate the booby trap? How much sand should he have used?Did you see that toss at the end!? How much would the idol weigh in lbs? (2.2 lb per kg)19,300 g7,720 cm3 or 7.72 L!42.5 lbs!
943. A 119 g solid cylinder has radius 1.80 cm and height 1.50 cm. Find sample’s density.1.5 cm1.8 cmmVDV = p r2 h= p (1.8 cm)2(1.5 cm)=cm3=
95this object sink in water? m8.2 cm5.1 cm4.7 cm4. A 153 g rectangular solidhas edge lengths 8.20 cm,5.10 cm, and 4.70 cm. Willthis object sink in water?(Find the object’s density and compare it to water’s density.)mVDV = l w h= 8.20 cm (5.10 cm)(4.70 cm)=cm3= 0.778< 1No; it floats.
96D5 D4 D3 D2 Galilean Thermometer Problem On a cold morning, a teacher walks into acold classroom and notices that all bulbsin the Galilean thermometer are huddledin a group. Where are the bulbs? At thetop of the thermometer, at the bottom or elsewhere?D11. Bulbs have essentially fixed massesand volumes. Therefore, each bulbhas a fixed density.D2D3D42. The surrounding liquid has a fixedmass, but its volume is extremelytemperature-dependent.D5
97Dliq D5 Vliq D4 D3 D2 3. The density of the liquid can be written as… so……if the liquid is cold:…but if it’s hot:Dliqmliqmliq==DliqVliqVliqOn a cold morning,where are the bulbs?AT THE TOP
100“what you started with” chemical:any substance that takes part in,or occurs as a result of,a chemical reaction*All matter can be considered to bechemicals or mixtures of chemicals.chemical reaction: a rearrangement ofatoms such that…“what you started with”differs from“what you end up with”reactantsproducts
103Law of Conservation of Mass: 2 Cu + H2O + CO2 + O2 CuCO3 + Cu(OH)2Copper “patina” is a mixture ofcopper(II) carbonate and copper(II) hydroxide.It has a characteristic green color.total mass total massof products of reactants=Pmass = Rmass
104Losing weight? Keeping the Law of onservation of mass in mind… When you lose weight, where does it go?Three ways, all of which involve excretion
105A proposed organic synthesis of tetrahydrocannabinol (THC) putting simpler substances together, usually in many steps, to make something more complexA proposed organic synthesis of tetrahydrocannabinol (THC)