Unit 1 Introduction to Chemistry

Unit 1Introduction to Chemistry

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Material Safety Data Sheet (MSDS) gives informationabout a chemical -- lists Dos and Donts; emergency procedures --

Ironwood 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 and West IndiesD = 1.49 g/cm3

How Toxic is Toxic?FlammableExplosiveRadioactiveCorrosiveIrritantCarcinogenicMutagenicTeratogenicChemicals may cause harm in many different ways:

the lethal dosage for 50% of the animals on which the chemical is testedLD50There 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

LD50 ExampleWhich is more toxic?Chemical A is more toxic because LESS is necessary to kill half of a given population

Chemical A: LD50 = 3.2 mg/kgChemical B: LD50 = 48 mg/kg

Science

The Functions of Sciencepure science applied sciencethe search for knowledge; factsusing knowledgein a practical waye.g., properties of aluminumstronglightweightgood conductor

Corning Glass

NASAs Problem Design a materialthat is clear and can with-stand extreme differences in temperature without fail-ing (cracking).Corning Glass Company FAILEDbut SUCCEEDED at making great cookware that can withstand extremes in temperature.Design a face shieldto protect and provideclear vision.

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. Aluminum Mining1850s: aluminum sold for $500 / lbCharles Martin HallDeveloped method to extract aluminum from bauxiteHalls methodAs a result, $0.30/lb

4-6 pounds bauxitecurrent1 lb Al+=

Charles Martin Hall (1863 - 1914) 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 (1863 - 1914) 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. Science attempts to establish cause/effect relationships Science can NEVER prove a cause/effect relationship, only make a correlation

risk-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.

How doesscientificknowledgeadvance?1. curiosity2. determination3. persistence4. good observations

The Scientific Method

** Key: Be a good observer. observationinferenceinvolves a judgmentor an assumptionuses the fivesenses

Types of DataObservations are also called data.qualitative data quantitative datacolorless liquid -- -- e.g., e.g., descriptions measurements 17 mL; 83oC (vs. clear liquid)

Candle Observation Activity

This cartoon is used the day after we perform the "Observations of a Burning Candle Lab" for a humorous set induction.A 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 scratched with the fingernail12. There is a wick13 which extends from top to bottom14 of the candle along its central axis15 and protrudes about 5 mm above the top of the candle16. The wick is made of three strands of string braided together17. A candle is lit by holding a source of flame close to the wick for a few seconds. Thereafter the source of flame can be removed and the flame sustains itself at the wick18. The burning candle makes no sound19. While burning, the body of the candle remains cool to the touch20 except near the top. Within about 1.5 cm of the top the candle is warm21 (but not hot) and sufficiently soft to 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 a region which emits yellow light31, bright but not blinding32. The flame has rather sharply defined sides33 but a ragged top34. The wick is white where it emerges from the candle35, but from the base of 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 emitted by the flame40, enough so that it becomes uncomfortable in 10 to 20 seconds if one holds his finger 10 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

Parts of the Scientific MethodIdentify an unknown.

Make a hypothesis:a testable predictionRepeatedly experiment to testhypothesis.procedure: order of events inexperimentvariable:any factor that couldinfluence the result (i.e., a recipe of what was done)A ScientificExperimentconclusion: must be supported with evidence from the data collected

Experiments must be controlled:Only one variable can change at a timeIndependent variable:Dependent variable: a variable you control and manipulate (x-axis)the variable you measure as you change I.V. (y-axis)

A Controlled Experiment?Make observationAsk questionDevelophypothesisTest hypothesis with anexperimentAnalyze dataand drawconclusionsHypothesis ISsupportedHypothesis is NOTsupportedDeveloptheoryTest hypothesis with furtherexperimentsRevisehypothesisWysession, Frank, Yancopoulos, Physical Science Concepts in Action, 2004, page 8Scientific Method

Scientific Law vs. Scientific Theorylaw: states what happens, i.e., a relationship between various quantities -- e.g., Newtons law of gravity,-- Laws are often written inthe form of an equation.

laws of conservation

Theory of Gravity,Atomic Theorytries to explain WHY orHOW something happenstheory:-- e.g., -- based on current evidence

images of nickel atomstaken by an STM a scanning tunneling microscope (STM) Phlogiston Theory of Burning1. Flammable materials contain phlogiston2. During burning, phlogiston is releasedinto the air3. Burning stops when object is out of phlogiston, or the surrounding air contains too much phlogiston.

(superceded by combustion theory of burning) Rob L. Brown, Sr. 1437 Tampa Avenue, Apt. J-432Bloomington, Illinois 61761Pay to theOrder of$________________________________DollarsIllinois State BankCHICAGO , ILLINOISMemo________________ ___________________________ Date_________:085936750: 4900861734Rob L. Brown, Sr. or Mary H. Brown1007 Shady LaneNormal, Illinois 61761Pay to theOrder of $________________________________DollarsNATIONAL CITY BANK OF MICHIGAN/ILLINOISSPRINGFIELD, ILLINOISMemo________________ ___________________________ Date_________:085936750: 4900861734Blank Checks26Chemistry

The BeginningThe Greeks believed therewere four elementsEarly practical chemistry:household goods, weapons, soap, wine, basic medicineearthwindfire waterD~~D___D___

AlchemyAllegedly, this substance would turn cheap metals into goldthe quest for the Philosophers Stone(~500 1300 C.E.)(the elixir, the Sorcerers Stone)Alchemical symbols for substances. . . . . . . . . . . .. . .GOLDSILVERCOPPER IRONSAND

transmutation:we cannottransmute elements into different elementschanging one substanceinto another

COPPER

GOLDPhilosophersStoneIn ordinary chemical reactionsAlchemy was practiced in many regions of theworld, including China and the Middle East.Alchemy arrived in western Europe around the year 500 C.E.Modern chemistry evolved from alchemy.

Contributions of alchemists: experimental techniques new glassware information about elements developed several alloys

What is chemistry?the study of matterand its changesAreas of Chemistryorganicphysicalinorganicbiochemistrystudies everythingexcept carbone.g., compoundscontaining metalsthe study of carboncontaining compoundsmeasuring physicalproperties ofsubstancesthe chemistry ofliving thingse.g., the meltingpoint of goldCareers in Chemistryresearch (new products)production (quality control)development (manufacturing)chemical salessoftware engineeringteaching

The skills you will develop by an earnest studyof chemistry will help you in any career field.

The Scope of Chemistrypharmaceuticalsnylon, polyester, rayon bulk chemical manufacturingpetroleum productssynthetic fibersacids, bases, fertilizersfuels, oils, greases, asphalt1 in 10,000 new drugs gets FDA approvalspandex,**sulfuric acid (H2SO4) = #1 chemical

Colloidal SilverUsed to treat fungal infections, skin rashes, Lyme disease, HIV/Aids and food poisoning

OK Supplements

Calcium, Cranberry, Fish Oil, Vitamin D, Lactobacilius

Chemistry impacts:everyoneall fields of endeavor

Government Regulation of ChemicalsThe various levels of government regulatechemicals to protect the:OSHAworkerFDAUSDACPSCconsumerEPAenvironment

OSHA: Occupational Safety and Health Admin.CPSC: Consumer product safety commission42

Manipulating Numerical DataGraphs

Bar Graphshows how many of something are in each category

# of studentsPie Graph shows how a whole is broken into parts

Percentage ofWeekly IncomeLine Graphshows continuous change

Stock Price over Timeyou will always use a line graph. In chemistry Elements of a good line graph2. axes labeled, with units

4. use the available space1. title3. neat

Graphing HWTimeTotal Dist. cycled (km)8 a.m.09 a.m.1210 a.m.2311 a.m.33noon421 p.m.502 p.m.573 p.m.634 p.m.68

Time (h)Distance Cycled (km)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 graphEssential Mathof Chemistry

Scientific Notationused to express very large or very small numbers. Also used to maintain correct SF.Form:(# from 1 to 9.999) x 10exponent 800= 8 x 10 x 10 = 8 x 102 2531 = 2.531 x 10 x 10 x 10 = 2.531 x 103 0.0014 = 1.4 10 10 10 = 1.4 x 103

(-) exponent = number < 1(+) exponent = number > 1Put in standard form 1.87 x 105 = 0.0000187 3.7 x 108 = 370,000,000 7.88 x 101 = 78.8 2.164 x 102 = 0.02164Change to scientific notation 12,340 = 1.234 x 104 0.369 = 3.69 x 101 0.008 = 8 x 103 1,000,000,000 = 1 x 1096.02 x 1023 =602,000,000,000,000,000,000,000

Using the Exponent KeyEXPEE

The EE or EXP or E key means times 10 to theHow to type out 6.02 x 1023:6EE.03226y x.0322x16.02EE320y x32x16.020 not or and notHow to type out 6.02 x 1023:6EE.0322WRONG!WRONG!TOO MUCH WORK.Also, know when to hit your () sign. (before the number, after the number, or either one)

4.3 x 10154.3 E 15or1.2 x 1052.8 x 1019

But instead is written=1.2EE5

92.8EE1Type this calculation in like this:This is NOT written4.3154.2857143 15Calculator gives4.2857143 E15or

6.5 x 10195.35 x 103 or 53502.9 x 10237.5 x 106 (8.7 x 1014) = 4.35 x 106 (1.23 x 103) =

5.76 x 1016 9.86 x 104 = 8.8 x 1011 x 3.3 x 1011 = 5.84 x 1013

All numerical data are the resultof uncertain measurements.8 mAccuracy and Precisionprecision: a measure of the degree offineness of a measurement; itdepends on the extent to which theinstrument is calibratede.g., vs. 8.00 mvs. 8.00000 m0.653 mWhen repeated, precise measurements yield similar answers each time.e.g., precise imprecise0.652 m0.654 m0.7 m0.8 m0.6 m

A good rule of thumb isIt is the % difference that is important.

accuracy:how close a measuredvalue is to the true valueThree types of error can affect accuracy.human error:method error:instrument error:-- minimize with repeated measurementse.g., parallax in measuring with a meter sticke.g., bathroom scale that always reads 5 lbs. too heavymistake in reading instrumentor recording resultsmeasuring device isimproperly calibratedusing measuring instrument improperly

Significant FiguresA student is combining separate water samples, all of differing volumes, into one large bucket. Samples A, B and C are 25.5 mL, 16.37 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.aboutMeasurement and PrecisionThe 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)262516.416.36050(think dashes) Identifying Significant FiguresCounting SF in a numberNon-zero numbers: ALWAYS count as SFZeroes Left: NEVER count as SF (0.000345)Middle: ALWAYS count as SF (5001)Right: sometimesw/ 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 = 6.022 x 1023)Conversions (1 in = 2.54 cm)

Relative to the non-zero numbersHow many Sig Figs?Measurement Number of SFMeasurement Number of SF25 g

0.030 kg

1.240560 x 106 mg

6 x 104 sec

246.31 g

20.06 cm

1.050 m0.12 kg

1240560. cm

6000000 kg

6.00 x 106 kg

409 cm

29.200 dm

0.02500 g2

2

7

1

5

4

42

7

1

3

3

5

4Now, determine the # of SF in Part A and B of the Sci. Not. HW (5 min)Sig Figs with CalculationsNote: 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)11.31 + 33.264 + 4.1 = 48.674Multiplication/DivisionRound the answer to the smallest number of SF found5.282 x 3.42 = 18.06444 rounded to 48.7 rounded to 18.1 (3.42 only has 3 SF)Back to the original questionA student is combining separate water samples, all of differing volumes, into one large bucket. Samples A, B and C are 25.5 mL, 16.37 mL and 51 mL, respectively. Once combined, what is the total volume of all the samples? 25.5 mL + 16.37 mL + 51 mL = 92.87 mL93 mLCould I write that as 93.0?NO!Round to the correct number of significant figures.Calculator says2 sig. figs.3 sig. figs.5 sig. figs.75.60.52839638760042008.4845E-47675.675.600* 3.8760 x 105388,000390,0000.528400.5280.538.5 x 1044.2000 x 103* 4.20 x 1034,2008.48 x 1048.4845 x 104* = requires scientific notationUnits must be carried into the answer, unless they cancel.0.64kg*ms25.2 kg (2.9 m) (18 s)(1.3 s)

=4.8 g (23 s) (18 s)(37 s)

=0.17 gsSolve for x.x + y = zx + y = z y yx = z yx and y are connected by addition. Separate them using subtraction. In general, use opposing functions to separate things.The +y and y cancel on the left, leaving us withSolve for x.x 24 = 13x 24 = 13 +24 +24x = 37x and 24 are connected by subtraction. Separate them using the opposite function: addition. The 24 and +24 cancel on the left, leaving us withNumerical ExampleSolve for x.F = k xF = k x

k

kx = Fk __ x and k are connected by multiplication. Separate them using the opposite function: division. ()__1kF = k x()__1k(or)The two ks cancel on the right, leaving us withNumerical ExampleSolve for x.8 = 7 x8 = 7 x

7

7x and 7 are connected by multiplication. Separate them using the opposite function: division. ()__178 = 7 x()__17(or)The two 7s cancel on the right, leaving us withx = 87 __ Solve for x.___ xBA= TRH___ BAH = xTROne way to solve this is to cross-multiply. BAH = xTRThen, divide both sides by TR. The answer is___BAHTRx =1TR()___1TR()___Solve for T2, whereP1 = 1.08 atmP2 = 0.86 atmV1 = 3.22 LV2 = 1.43 LT1 = 373 K

P1V1T2 = P2V2T1____ T1P1V1= P2V2T2____ 1P1V1()____1P1V1()____T2 =P1V1______P2V2T1130T2 =(1.08 atm)(3.22 L)_____________________(0.86 atm)(1.43 L)(373 K)=KSI Prefixeskilo-(k) 1000deci-(d) 1/10centi-(c) 1/100milli-(m) 1/1000Also,1 mL = 1 cm3and 1 L = 1 dm3You will be responsible for knowing these!

Conversion Factors andUnit CancellationHow many cm are in 1.32 meters?conversion factors:equality:or 1.32 m= 132 cm1 m = 100 cm

______1 m100 cmWe use the idea of unit cancellationto decide upon which one of the twoconversion factors we choose.______1 m100 cm1 m100 cm(or 0.01 m = 1 cm)How many m is 8.72 cm?conversion factors:equality:or 8.72 cm= 0.0872 m1 m = 100 cm______1 m100 cmAgain, the units must cancel.______1 m100 cm1 m100 cm

How many kilometers is 15,000 decimeters?

15,000 dm=1.5 km1,000 m1 km10 dm1 mHow many seconds is 4.38 days?= 378,432 s1 h60 min24 h1 d1 min60 s____()()____()_____4.38 d3.78 x 105 sIf we are accounting for significant figures, we would change this to

4. Convert 41.2 cm2 to mm2 41.2 cm2Recall that1 cm = 10 mm=4,120 mm21 cm2102 mm2( )2( )2

SI-US Conversion FactorsEqualityConversion FactorsLengthVolumeMass2.54 cm = 1 in.1 m = 39.4 in.946 mL = 1 qt1 L = 1.06 qt453.6 g = 1 lb1 kg = 2.20 lb 1 in2.54 cm 39.4 in 1 m 1 m 39.4 in.946 mL 1 qt 1 qt 946 mL 1.06 qt 1 L 1 L 1.06 qt 453.6 g 1 lb 1 lb 453.6 g 2.20 lb 1 kg 1 kg 2.20 lb2.54 cm 1 inandandandandandand82Dominoes Activity

Simple MathwithConversion FactorsFind area of rectangle.A = L . W= (4.6 cm)(9.1 cm) 9.1 cm= 42cm2. cm4.6 cmConvert to m2. 42 cm2()______100 cm1 m2= 0.0042 m2Convert to mm2. 42 cm2()______ 1 cm10 mm2= 4200 mm2cm.cmFor the rectangular solid: Find volume.Length = 14.2 cm Width = 8.6 cm Height = 21.5 cmV = L . W . H= (14.2 cm)(8.6 cm)(21.5 cm) =2600cm3Convert to mm3. 2600 cm3()______ 1 cm10 mm3= 2,600,000 mm3= 2.6 x 106 mm3mm and cm differ by a factor of.

mm2 cm2 .

mm3 cm3 .101001000Density how tightly packed the particles are Density = Typical units: g/cm3 for solids g/mL for fluids

m V D liquids and gases

Glass: liquid or solid?To find volume, use 1. a formula water displacement V = l w hV = p r2 h

V = ?

VfinalVinitialVobject = Vfinal Vinitial2. ** Density of water = The density of a liquid or solid is nearly constant,no matter what the samples temperature1.0 g/mL = 1.0 g/cm3 Things that are less dense floatin things that are more dense.

D < 1 g/cm3Density of gases is highly dependent on temperatureD < 1 g/cm3D > 1 g/cm3D < 1 g/cm3(And things that are more dense sinkin things that are less dense.

Will Bowling Balls sink or float in H2O?21.6 cm in diameterVsphere = 4/3 p r3V = 4/3 p (10.8 cm)3V = 5,276.7 cm3If DBB > 1, it will sinkIf DBB < 1, it will floatSince the mass of a BB varies, lets figure out at what mass it will sink v. floatm = (1.00 g/cm3)(5276.7 cm3) m V Dm = 5276.7 gm = D Vor 11.6 lbsDensity Calculations1. A sample of lead (Pb) has mass 22.70 g and volume 2.000 cm3. Find samples density.

m V D

2. Another sample of lead occupies 16.2 cm3 of space. Find samples mass.

m = D V= 184

= 11.35gV Indiana 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!

3. A 119 g solid cylinder has radius 1.80 cm and height 1.50 cm. Find samples density. 1.5 cm 1.8 cm m V DmV = p r2 h

= p (1.8 cm)2(1.5 cm)= 15.268

= 7.79cm34. A 153 g rectangular solid has edge lengths 8.20 cm, 5.10 cm, and 4.70 cm. Will this object sink in water? 8.2 cm5.1 cm4.7 cm m V D

(Find the objects density and compare it to waters density.)mV = l w h= 8.20 cm (5.10 cm)(4.70 cm)

= 196.55

= 0.778cm3< 1No; it floats.Galilean Thermometer ProblemOn 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?1. Bulbs have essentially fixed masses and volumes. Therefore, each bulb has a fixed density. 2. The surrounding liquid has a fixed mass, but its volume is extremely temperature-dependent.

D1D2D3D4D5D1D2D3D4D53. The density of the liquid can be written as

so if the liquid is cold: but if its hot: mliq=On a cold morning,where are the bulbs?AT THE TOP Vliqmliq Dliq=VliqDliq

Osmium76Os

Basic Concepts in Chemistry

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 thatwhat you started withdiffers fromwhat you end up with

productsreactantsmethane + oxygen + H2O(g)carbondioxide O2(g)CO2(g)CH4(g)+water+22ReactantsProductsNaOH(aq)waterNa(s)H2O(l)H2(g)2sodium22hydrogensodiumhydroxide++++ReactantsProductsLaw of Conservation of Mass:total mass total massof productsof reactantsPmass = Rmass=

2 Cu + H2O + CO2 + O2 CuCO3 + Cu(OH)2

Copper patina is a mixture ofcopper(II) carbonate and copper(II) hydroxide.It has a characteristic green color.

Losing weight?Keeping the Law of onservation of mass in mindWhen you lose weight, where does it go?Three ways, all of which involve excretion

synthesis:putting simpler substances together, usually in many steps, to make something more complexA proposed organic synthesis of tetrahydrocannabinol (THC)