Dear Honors Chemistry Student,

Transcription

1 Dear Hnrs Chemistry Student, This packet is designed t prvide students entering Hnrs Chemistry with imprtant chemistry-based mathematical skills and chemistry cntent befre the start f the schl year in rder t ensure success thrughut the academic year. A written assessment f the tpics will be cnducted during the secnd week f the schl year in September. The packet is brken up int three different prtins. The chemistry cntent prtin f this packet will require an utline creatin. Each utline tpic requires a hand-written summary sheet that will act as a study guide fr the written assessment. Each summary sheet shuld be a single standard page (8.5" x 11") using bth-sides f the paper. Only the riginals (nt cpies) f these sheets will be cllected and graded. The mathematical prtin f this packet prvides students with an pprtunity t learn and practice mathematical skills specific t chemistry and its related tpics. ALL prtins will be assessed n the written assessment in September. In rder t help students prepare, bth vide tutrials and guiding questins are prvided in this packet. These are nt all-encmpassing resurces, thugh. Yu will als have access t the nline cpy f the text bk fr the cmpletin f this packet. All Hnrs Chemistry students are expected t cmplete this assignment, regardless f the date f enrllment in the curse. D nt hesitate t reach ut if there are any questins regarding this packet. We lk frward t yur enrllment in Hnrs Chemistry fr the 2018/2019 academic schl year! Sincerely, The Hnrs Chemistry Teachers

2 Resurces Vide Tutrials G t Tyler Dewitt website at and watch the fllwing vides OR G t Bzeman Science website at Watch the fllwing vides: Unit 1: Intrductin Factr-Label Methd Unit 1: Intrductin Scientific Methd Unit 1: Intrductin Significant Digits Unit 2: Matter & Atmic Thery Histry f the Atm Unit 2: Matter & Atmic Thery Matter Unit 2: Matter & Atmic Thery Prperties f Matter OR G t Khan Academy website at the fllwing YuTube links. Significant Figures: Calculatins with Significant Figures -- Multiplying and Dividing: Adding and Subtracting: Metric Cnversins:

3 Part 1: Chemistry Cntent Guiding Questins These general tpics and subsequent guiding questins will be used t create yur utline. Each general tpic requires the cmplete f an utline sheet. The requirements fr the sheets are given n the previus page. 1. Tpic #1: Intrductin t Chemistry What is a chemical? Hw is matter measured? Describe the difference between mass and vlume. Describe what each term is and what it is made f Atm Element Cmpund Fr the fllwing prperties, define the prperty, and describe hw the prperty can be measured r bserved, and give 3 examples fr each. Extensive Intensive Physical Chemical Describe the atms in the fllwing states f matter Slid Liquid Gas Plasma Explain the differences between a physical and chemical change. Why is a phase change a physical change and nt chemical change? Describe a chemical reactin in terms f reactants and prducts. Explain hw the law f cnservatin f energy and the law f cnservatin f mass can hld true during a chemical reactin. Describe the tw types f mixtures, hw are the tw mixtures identified. Cmpare and cntrast hmgeneus mixtures and cmpund. Define pure substance. On the peridic table belw identify the lcatin f grups / families perids metals nnmetals metallids nble gases Cmpare and cntrast the characteristics f metals and nnmetals.

4 2. Tpic #2: Quantitative Chemistry What is the difference between a quantitative bservatin and a qualitative measurement? What are the advantages t the metric r SI system? Make a chart f the seven base units f the SI system. In the chart include what each unit measures, the unit name, the quantity symbl and the unit abbreviatin. Hw is a derived unit different frm and base unit? Make a chart f the seven derived SI units; include the quantity measured, the quantity symbl, the unit name, the unit abbreviatin and the equatin used t derive the unit. Explain density as it relates t chemistry. 3. Tpic #3: Atmic Thery Demcritus (date) initial view f the atm image/example f what the Demcritus Atm wuld lk like (based n the descriptin) Daltn (date) Daltn s atmic thery explain Daltn s mdel f the atm image f Daltn s mdel J.J. Thmsn (date) particle fund by J.J. Thmsn explanatin f the experiment used t find the particle image f the experiment the mdel J.J. Thmsn develped, descriptin and image Rutherfrd (date) explain the experiment perfrmed by Rutherfrd image f the experiment develpment made twards the atm based n the experiment Image f the Rutherfrd atmic mdel Millikan (date) experiment used by Millikan develpment made based n the experiment image f the experiment inferences that culd be made abut the atm Bhr (date) Describe hw Bhr s mdel f the atm is different than Rutherfrd s image f the Bhr s Atmic Mdel Quantum Mdel Describe hw the Quantum mdel is different that the Bhr Mdel Histry f Atmic Thery Part 1: Part2:

5 Directins: Fill in the blanks n the answer frm (after the stry) with the wrds belw atms cnservatin f matter cathde ray tube Plum Pudding Demcritus atmic subatmic particle Aristtle (3) Electrns prtns neutrns Gld Fil Daltn Slar System JJ Thmsn Albert Einstein Alpha multiple prprtins definite prprtins nucleus energy levels empty The Stry f the Atm Ernest Rutherfrd negative Brwnian Mtin Lavisier Mre than 2,400 years ag, the Greek philspher (1) _ prpsed the existence f very small, indivisible particles, each f which was called (2). Unfrtunately the prminent philspher (3) _ argued that these particles did nt exist and the idea was largely frgtten fr nearly 2000 years. The first evidence that these particles existed was fund in 1778 when the French scientist (4) _ fund that the mass f the prducts f a reactin always equaled the mass f the reactants r starting material in a chemical reactin. He prpsed that matter was nt created nr destryed in a reactin but simply rearranged. This statement became knwn as the law f (5), Shrtly after the first (6) _ thery was develped by (7) _ wh cmpiled all the evidence fr the existence f these particles. Tw new laws were revealed in this Atmic thery. The law f (8) _ states that the rati f elements in any given cmpund is always the same. Thus every water mlecule has 2 hydrgen atms and 1 xygen atm. The law f (9) _ states that elements can cmbine in different ratis t frm different cmpunds. An example f this law is fund in the existence f bth carbn mnxide, CO and carbn dixide, CO2. The atmic thery stated that these particles were indestructible and that different elements cnsisted f different particles that differ in size and shape. Despite all f the evidence fr the existence f these particles their existence was still up fr debate. Still evidence cntinued t munt in their favr. In 1898 (10) _discvered the first (11) _ when he perfrmed his histric (12) _ experiment pictured belw. In this experiment he sent an electrical charge thrugh a Crkes Tube and fund that the beam f light that appeared deflected tward the psitive plate thus indicating that beam f light was made up f (13) _ charged particles. He called the particles (14) _ and

6 thrugh careful calculatins was able t determine that their mass was 1/1000 th the mass f Hydrgen atm. In rder t accunt fr the negatively charged particles he prpsed the (15) _ mdel f the atm in which electrns were embedded in the psitively charged clud that was the atm. Still there was debate ver the existence f atms. Then in 1905 a German scientist named (16) _ prved the existence f the atm with his (17) _ experiment. In the mid 1800 s Dr. Rbert Brwn had discvered that pllen grains when drpped in water were jstled abut almst as if they were dancing. Einstein realized in 1906 that the mvement f the pllen grains was caused by atms hitting the grains. By carefully measuring the mvement f the pllen grains Einstein was able t calculate the size f an atm which it turns ut is extremely small. The width f a single human hair is 1,000,000 atms thick. The atm is s small that there are mre atms in a single glass f water than there are glasses f water in all the wrld s ceans cmbined. Then in 1909 (18) _ perfrmed his famus (19) _ experiment shwn belw. In this experiment Rutherfrd fired (20) _ particles which are tw prtn, tw neutrn helium nuclei at a very thin sheet f gld fil. He expected t see the particles rip right thrugh the fil like shting a gun at a sheet f tissue paper. What he fund astnished him. Rughly tw percent f the particles were deflected in sme way and 1 in 8000 actually bunced ff the fil and came back at him. He cncluded that at the center f the atm was a dense psitively charged (21) _ that

7 deflected the psitively charged alpha particles. The rest f the particles passed straight thrugh the atm because the rest f the atm is mstly (22) _ space. This lead Rutherfrd t prpse his (23) _ mdel f the atm in which the electrns rbit the nucleus like planets rbiting the sun. Of curse the atm we knw tday is a lt different than Rutherfrd s atm. Our atm has a nucleus with bth psitively charged (24) _ and neutral (25) _ as well as electrns existing in (26) _ instead f rbits. Still the Rutherfrd mdel serves as nice apprximatin f an atm and represented the first time that we realized that the atm had a nucleus, was mstly empty space and had electrns n the utside f the atm. ANSWERS 1. _ 10. _ 19. _ 2. _ 11. _ 20. _ 3. _ 12. _ 21. _ 4. _ 13. _ 22. _ 5. _ 14. _ 23. _ 6. _ 15. _ 24. _ 7. _ 16. _ 25. _ 8. _ 17. _ 26. _ 9. _ 18. _

8 Tpic #4: Descriptive Chemistry What infrmatin abut element des the atmic number give? Hw is the mass number fund? Why is it imprtant when discussing istpes? Describe hw prtium, deuterium and tritium are similar and hw are they different. Describe the difference between relative atmic mass and average atmic mass. List the Names, symbls, atmic number, mass number, and atmic mass f the first twenty elements. ATOMS AND ISOTOPES The atmic number tells yu the number f prtns an element has. Ntice hw n tw elements have the same atmic number. As a result, yu can identify an element s identity based upn the number f prtns it cntains. If an element is neutral, meaning it has n charge, then the atmic number can tell yu the number f electrns as well if the atm is neutral (n charge). The atmic mass is the weighted average f the mass numbers f all istpes (istpes have the same number f prtns, but a different number f neutrns) f an element fund in nature. The unit fr atmic mass is amu (Mdel 1). This number is the decimal number seen n the peridic table. The 3 particles f the atms are: Their respective charges are: a. _ a. b. b. _ c. c. Istpe Ntatin Mass number is nt represented n the peridic table. Hwever, it tells us the number f prtns plus neutrns fr a particular istpe f an element. Ins are atms that have lst r gained electrns. If an atm lses an electrn, it frms an in with a psitive charge (catin). Fr example, when sdium lses an electrn it becmes Na +1. When an atm gains electrns, it becmes an in with a negative charge (anin). Fr example, when xygen gains 2 electrns it becme

9 1. What des A stand fr and hw d yu calculate A? Give an algebraic frmula. 2. What des Z stand fr? Which subatmic particle des Z represent? 3. When can the atmic number tell yu the number f electrns? 4. If an atm gains 2 electrns, what charge will it frm? 5. If an atm lses 2 electrns, what charge will it frm

10 Directins: Lcate each element n the peridic table and write dwn the atmic number and atmic mass. Use that infrmatin t determine the number f prtns, electrns, and neutrns in an atm f that element. Element Name Nuclear Symbl Atmic Number Mass Number Number f Prtns Number f electrns Number f Neutrns Charge Calcium Fe Ca Sulfur

11 Part II: Math Skills fr Chemistry Students Mathematics is used widely in chemistry as well as all ther sciences. Mathematical calculatins are abslutely necessary t explre imprtant cncepts in chemistry. Withut sme basic mathematics skills, these calculatins, and therefre chemistry itself, will be extremely difficult. Hwever, with a basic knwledge f sme f the mathematics that will be used in yur chemistry curse, yu will be well prepared t deal with the cncepts and theries f chemistry. This dcument describes the math skills yu will need t be successful this year in chemistry. Yu will be expected t d algebra, scientific ntatin, unit cnversins, dimensinal analysis and graphing. Yu will be tested n these skills within the first 10days f schl. After the test, the skills are nt dne with. THESE SKILLS WILL BE USED ALL YEAR. It is EXPECTED and TAKEN FOR GRANTED that all students have the necessary math skills. Yu can review nw and get cmfrtable with the math r yu can struggle with it fr the rest f the year. The chice is yurs! Algebra and Rearranging Equatins 1 When slving chemistry prblems yu will ften be required t rearrange an equatin t slve fr an unknwn. Three things t remember: 1) Use the ppsite Functin t mve smething frm ne side t the ther. 2) What yu d t ne side, yu must d t the ther side f the equatin. 3) Get the variable n the tp and by itself. 4) The fllwing examples will help illustrate Example 1 2a = (27 3a)5 T slve: 1) Expand the right side by multiplying each term. 5 x 27 = x 3a = 15a Rewritten Equatin: 2a = a 2) Grup Like terms tgether. The main idea here is t get all the a terms n ne side and the terms withut a n the ther side by using the ppsite functin t mve terms frm ne side f the equatin t the ther side f the equatin. Remember that whatever yu d t ne side yu must d t the ther side f the equatin. In this case, t mve the 15a t the side with 2a yu must add 15a t bth sides f the equatin. 2a = a + 15a +15a 17a = 135

12 3) Islate unknwn. Divide bth sides by the a s cefficient (ppsite f multiplying 17 x a). 17a 135 = ) Slve. a = 7.94 Runding Numbers 2 Anther issue we need t deal with when we perfrm peratins is hw t state the answer. Fr example, if we are dividing a 20-centimeter wire int 3 equal pieces, we wuld divide 20 by 3 t get the length f each piece. If we tk the time t wrk this divisin ut by hand -- ack! -- we wuld get 20 / 3 = The 6 repeats frever. Hw d we reprt this number? We rund t sme usually predetermined number f digits r decimal places. By "digits" we mean the ttal number f numbers bth left and right f the decimal pint. By "decimal places" we specifically refer t the number f numbers t the right f the decimal pint. Fr cmparisn, let's try runding this number t 2 decimal places -- tw numbers t the right f the pint. T rund, lk at the digit after the ne f interest -- in this case the third decimal place -- and use the rule: In ur example: if the digit is 0, 1, 2, 3 r 4 rund dwn if the digit is 5, 6, 7, 8 r 9 rund up ^ the next digit is 6 s we rund up, giving 6.67 as the desired answer. If instead we had been asked t rund the number 20/3 t 2 digits the answer wuld have been 6.7 (tw digits, ne f which is a "decimal place"). Smetimes runding is the result f an apprximatin. If yu had 101 r 98 meters f sme wire, in each case yu wuld have "abut 100 meters." We will rund many f ur answers in science because the numbers will ften be reprting measurements. Numbers representing measurements are nly as accurate as the device used fr measuring. Fr example, we culd use a standard meter stick marked ff in centimeters t measure the length f a wire as 15 cm. If smetime later we cut the wire in pieces, reprting the size f a piece f the wire t nine r ten decimal places wuld nt make sense. It is just as imprtant t knw WHEN t rund as HOW t rund. In any math prblem yu shuld wait until the end t rund; Only the final answer shuld be runded. Carry as many significant digits as yu can thrughut the prblem. On a calculatr, the mst efficient way t carry the maximum is t d all the calculatin n the calculatr. Arrange the prblem s that yu d nt have t cpy an intermediate answer nly t re-enter it int the calculatr.

13 Runding Practice Prblems: Rund the fllwing numbers as indicated. T fur figures: x x T the nearest whle number: x 10 4 T ne decimal place: T the nearest thusandth:

14 Percentage Calculatins 3 Cnverting raw numbers t percentages is easy nce the parts are defined. A percentage is the target ver the ttal multiplied by ne hundred percent. percentage = part 100% ttal There are thirty peple in the classrm. Of them, seventeen are male. What is the percentage f males in the classrm? 'Seventeen males' is the part we have defined. 'Thirty peple' is the ttal. Seventeen divided by thirty times ne hundred is Males are peple, s we cancel the units. The answer is 56.7 percent. In many cases, the mst difficult part f using percentages is identifying the part and the ttal. Percentages d nt have any ther unit attached t them ther than the percent. After dividing ne unit by the same type f unit and cancelling the units, which shuld make sense. Percentage Practice Prblems: 1. In 1995, 78 wmen were enrlled in chemistry at a certain high schl while 162 men were enrlled. What was the percentage f wmen taking chemistry? The percentage f men? 2. A penny has a ttal mass f 3.1g. Zinc makes up 2.9g f the penny. What is the percentage f zinc in the penny?

15 Scientific Ntatin 4 There are many very large and very small numbers in scientific studies. Hw wuld yu like have t calculate with: 1 Daltn = 0.000,000,000,000,000,000,000,00165 g r 1 ml = 602,200,000,000,000,000,000,000 atms Yu can streamline large r small numbers with scientific ntatin. The standard is that yu mve the decimal pint t the left r right until yu get a number greater than 1 but less than 10. Adjust the expnent f ten (10 x ) t reflect the number f times the decimal place was mved. The nly questin yu might have truble with is WHICH WAY t mve the decimal. The easy way t remember that is: numbers that are less than ne have negative expnent numbers in the scientific ntatin frm, and numbers that are larger than ne have psitive expnent numbers. Think f the change as creating a new number with tw parts, a digit part and an expnent part, frm the ld number. T change 0.000,000,000,000,000,000,000,00165 int scientific ntatin, mve the decimal t the right 24 times s it is between the 1 and 6 (1.65 is greater than 1 but less than 10). Since the number began as a value less than 1 (a decimal), the decimal was mved t the right and the sign f the expnent is negative ,000,000,000,000,000,000,00165 = 1.65 x ,200,000,000,000,000,000,000 = x Here are sme examples f scientific ntatin: = 1 x = x = 1 x = x = 1 x = 4.82 x = 1 x = 8.9 x 10 1 (nt usually dne) 1 = /10 = 0.1 = 1 x = 3.2 x 10-1 (nt usually dne) 1/100 = 0.01 = 1 x = 5.3 x /1000 = = 1 x = 7.8 x /10000 = = 1 x = 4.4 x 10-4

16 Scientific ntatin can als be written in anther frm. Using the values frm abve: 0.000,000,000,000,000,000,000,00165 = 1.65 x r 1.65 x 10 ^ ,200,000,000,000,000,000,000 = x r x 10^23 The "E" in the number stands fr expnent. Yur scientific calculatr will use the numbers in the shrtened frm, usually best represented by the "E" frm. Scientific Ntatin n Yur Calculatr 4 When yu are using yur calculatr, typing "smething times ten t the smething" ver and ver again gets t be a pain. Mst calculatrs have an "EE" buttn, t help yu ut. (Nte that when yu type the EE key, mst calculatrs simply display "E"! D nt be alarmed by this. This is nt the E that means errr.) Be careful! It's easy t make the fllwing cmmn mistake: Remember that EE -- times ten t the -- is nt the same as ^ -- "t the"! Make sure that the number in scientific ntatin is put int yur calculatr crrectly. Read the directins fr yur particular calculatr. Fr inexpensive scientific calculatrs: 1. Punch the number (the digit number) int yur calculatr. 2. Push the EE r EXP buttn. D NOT use the x (times) buttn!! 3. Enter the expnent number. Use the +/- buttn t change its sign. 4. Vila! Treat this number nrmally in all subsequent calculatins. T check yurself, multiply 6.0 x 10 5 times 4.0 x 10 3 n yur calculatr. Yur answer shuld be 2.4 x If yu dn t have a scientific calculatr: Yu will need t be familiar with expnents since yur calculatr cannt take care f them fr yu. Additin and Subtractin: All numbers are cnverted t the same pwer f 10, and the digit terms are added r subtracted. -2 Example: (4.215 x 104 ) + (3.2 x ) = (4.215 x ) + (0.032 x ) = x 10-2 Example: (8.97 x 10 ) - (2.62 x 10 ) = (8.97 x 10 ) - (0.262 x 10 ) = 8.71 x 10 Multiplicatin: The digit terms are multiplied in the nrmal way and the expnents are added. The end result is changed s 6 that there 3 is nly ne nnzer (6+3) digit t the left 9 f the decimal. 10 Example: (3.4 x 10 )(4.2 x 10 ) = (3.4)(4.2) x 10 = x 10 = x 10-5 Example: (6.73 x 10 )(2.91 x 10 2 ) = (6.73)(2.91) x 10 (-5+2) = x 10-3 = x 10-2

17 Divisin: The digit terms are divided in the nrmal way and the expnents are subtracted. The qutient is changed (if necessary) s that there is nly ne nnzer digit t the left f the decimal. 6 2 (6-2) 4 3 Example: (6.4 x 10 )/(8.9 x 10 ) = (6.4)/(8.9) x 10 = x 10 = 7.2 x 10 (t 2 significant figures) 3 Example: (3.2 x 10 )/(5.7 x 10-2 ) = (3.2)/(5.7) x 10 3-(-2) = x 10 5 = 5.6 x 10 4 (t 2 significant figures) Scientific Ntatin Practice Prblems 5 : Write the fllwing numbers in scientific ntatin ,926,300, Take the numbers ut f scientific ntatin x x x x x x x x x x 10 2 Use Scientific Ntatin (and nly the scientific ntatin!) t find the answer t the fllwing prblems: x * 5.4 x 10 2 =? x x =? x 10 5 * 1.96 x =? x 10 3 * 2.34 x x 10-2 =? x x x 10 4 =?

18 Significant figures 5 The last digit f a measurement expressin is uncertain. That is because the last digit is estimatin. Significant figures in a measurement expressin cmprise all digits that knwn with certainty, plus ne digit that is uncertain. PLACEHOLDERS ARE NOT SIGNIFICANT. Rules fr determining the number f significant figures in a given value: 1. All nn-zer digits are significant. 2. All zers between tw nnzer digits are significant. (aka: sandwich rule). PRACTICE: Determine the number f significant figures in each f the measurements belw L L g g 5.3,400,008 ml 3. Trailing zers are significant nly if there is a decimal pint r a bar drawn ver the zer PRACTICE: determine the number f significant figures in each f the measurements belw: ,00 g _ 2.345, 000 cm L mg 4. Zers in the beginning f a number whse nly functin is t place the decimal pint are nt significant. Ex: has 2 significant figures. 5. Zers fllwing a decimal significant figure are significant Ex: has 3 significant figures PRACTICE: determine the number f significant figures in each f the measurements belw: ml kg g L g cm

19 Significant figures - Determine the number f significant figures in the fllwing measurements ml L L ,876, mm g ,008 g ,000 cm g ,000 cm cm ,000 ml cm g cm ,008 ml cm L x ,000 g x g x ,010g Rule fr Multiplying and Dividing Limit and rund t the least number f significant figures f any f the factrs. Example: 23.0 cm x 432 cm x 19 cm = 188,784 cm 3 = 190,000 cm 3 since 19 cm has nly tw significant figures Rule fr Adding and Subtracting Limit and rund yur answer t the least number f decimal places Example: ml ml ml = ml = ml since 46.0 ml has nly ne decimal place Perfrm the fllwing peratins expressing the answer in the crrect number f significant figures m x m = 2.1,035 m 2 / 42 m = ml ml + 6 ml = g 28.9 g = cm cm cm =

20 Units f Measure 6 In science, when quantities are measured r calculated, they must be given prper units. A measurement withut a unit specificatin really des nt make much sense. Imagine if smene tld yu that Mt. Everest is 10 4 tall. Withut a unit specificatin this number shuld mean nthing t yu. There is a set f fundamental physical quantities - sme f which yu might already have sme experience with - which frm a srt f "building blck" fr measurements and calculatin. The THREE fundamental r standard "building blcks" that are needed are: Length, Mass, and Time. Yu are prbably familiar with the fundamental units f length, mass and time in the American system: the yard, the pund, and the secnd. The ther cmmn units f the American system are ften strange multiples f these fundamental units such as the tn (2000 lbs.), the mile (1760 yds.), the inch (1/36 yd.) and the unce (1/16 lb.). Mst f these units arse frm accidental cnventins, and s have few lgical relatinships. Mst f the wrld uses a much mre ratinal system knwn as the metric system (the SI, Systeme Internatinal d'unites, internatinally agreed upn system f units) with the fllwing fundamental units: The meter fr length. Abbreviated "m". The kilgram fr mass. Abbreviated "kg". (Nte: kilgram, nt gram, is the standard.) The secnd fr time. Abbreviated "s". Base 10 System f Units All f the unit relatinships in the metric system are based n multiples f 10, s it is very easy t multiply and divide. The SI system uses prefixes t make multiples f the units. All f the prefixes represent pwers f 10. The table belw gives prefixes used in the metric system, alng with their abbreviatins and values. Metric Prefixes Prefix Abbreviatin Value Prefix Abbreviatin Value deci d 10-1 deca da 10 1 centi c 10-2 hect h 10 2 milli m 10-3 kil k 10 3 micr m 10-6 mega M 10 6 nan n 10-9 giga G 10 9 pic p tera T 10 12

21 Other Systems f Units and Relatins t SI System The United States, unfrtunately, is ne the few cuntries in the wrld that has nt yet made a cmplete cnversin t the metric system. (Even Great Britain has adpted the SI system; s what we used t call "English" units are n mre - they are strictly "American"!) As a result, yu are frced t learn cnversins between American and SI units, since all science and internatinal cmmerce is transacted in SI units. Frtunately, cnverting units is nt difficult. Yu can find tables listing the cnversins between American and SI units Strictly speaking, the cnversin between kilgrams and punds is valid nly n the Earth since kilgrams measure mass while punds measure weight. Hwever, since mst f yu will be remaining n the Earth fr the freseeable future, we will nt yet wrry abut such details. (If yu're interested, the unit f weight in the SI system is the newtn, and the unit f mass in the American system is the slug.) Cnversin Factrs 6 A cnversin factr is a factr used t cnvert ne unit f measurement int anther unit. A simple cnversin factr can be used t cnvert meters int centimeters, r a mre cmplex ne can be used t cnvert miles per hur int meters per secnd. Since mst calculatins require measurements t be in certain units, yu will find many uses fr cnversin factrs. What must always be remembered is that a cnversin factr has t represent a fact; because the cnversin factr is a fact and nt a measurement, the numbers in a cnversin factr are exact. This fact can either be simple r cmplex. Fr instance, yu prbably already knw the fact that 12 eggs equal 1 dzen. A mre cmplex fact is that the speed f light is 3.00 x 10 8 meters/sec. Either ne f these can be used as a cnversin factr, depending n the type f calculatin yu might be wrking with. Dimensinal Analysis 6 Frequently, it is necessary t cnvert units measuring the same quantity frm ne frm t anther. Fr example, it may be necessary t cnvert a length measurement in meters t millimeters. This prcess is quite simple if yu fllw a standard prcedure called dimensinal analysis (als knwn as unit analysis r the factr-label methd). Dimensinal analysis is a technique that invlves the study f the dimensins (units) f physical quantities. It is a cnvenient way t check mathematical equatins. (There are ther names fr the very same idea, fr instance, unit cnversin r factr label r factr-unit system.) Dimensinal analysis invlves cnsidering the units yu presently have and the units yu wish t end up with, as well as designing cnversin factrs that will cancel units yu dn t want and prduce units yu d want. The cnversin factrs are created frm the equivalency relatinships between the units. Suppse yu want t cnvert meters int millimeters. In this case, yu need nly ne cnversin factr that will cancel the meters unit and create the millimeters unit. The cnversin factr will be created frm the relatinship 1000mL = 1m.

22 In the abve expressin, the meter units will cancel and nly the millimeter unit will remain. Example 1: Cnvert 1.53 g t cg. The equivalency relatinship is 1.00g = 100 cg, s the cnversin factr is cnstructed frm this equivalency in rder t cancel grams and prduce centigrams. Example 2: Cnvert in. t ft. The equivalency between inches and feet is 12in = 1 ft. The cnversin factr is designed t cancel inches and prduce feet. Each cnversin factr is designed specifically fr the prblem. In the case f the cnversin abve, we need t cancel inches, s we knw that the inches cmpnent in the cnversin factr needs t be in the denminatr. Smetimes, it is necessary t insert a series f cnversin factrs. Suppse we need t cnvert miles t kilmeters, and the nly equivalencies we knw are 1mi = 5,280ft, 12in = 1ft, 2.54 cm = 1 in, 100 cm = 1m, 1000m = 1km. We will set up a series f cnversin factrs s that each cnversin factr prduces the next unit in the sequence. Example 3: Cnvert 12 mi t km. In each step, the previus unit is canceled and the next unit in the sequence is prduced. Cnversin factrs fr area and vlume can als be prduced by this methd. Example 4: Cnvert 1500 cm 2 t m 2. Example 5: Cnvert 12 in 3 t cm 3.

23 Dimensinal Analysis Practice Prblems 3 : 1. What is 1.50 mm in km? 2. Hw many nansecnds are in 1.50 days? 3. A car is ging 60.0 MPH. Hw fast is that in ft/sec? 4. A car is ging 62.0 MPH. Hw fast is that in KPH? 5. Light travels at 3.00 x 10 8 m/sec. Hw fast is that in MPH?

24 Algebra Review: Slving fr Unknwn Variable Directins: Slve the fllwing fr the indicated variable. 1. Slve fr n. PV =nrt 2. Slve fr m. q=mcδt 3. Slve fr v. D = m V 4. Slve fr T 1. P 1 V 1 = P 2 V 2 T 1 T 2 5. Slve fr L. M = n L 6. Slve fr V 2. P 1 V 1 = P 2 V 2 T 1 T 2 7. Slve fr T f. q=mc (T f T i ) 8. Slve fr m. D = m V

25 Part III: Identifying Labratry Equipment Intrductin Scientists use a variety f tls t explre the wrld arund them. Scientific tls are very imprtant in the advancement f science. The type f tls scientists use depends n the prblems they are trying t slve. A scientist may use smething as simple as a metric ruler t measure the length f a textbk. In a different investigatin, the same scientist may use a thermmeter t measure the temperature f a unknwn biling liquid. In this activity, yu will identify pieces f labratry equipment likely t be used in a chemistry labratry. Yu will als learn the functin f each piece f labratry equipment. Prblem What are the names and functins f sme f the pieces f labratry equipment fund in a typical chemistry labratry? Prcedure 1. Lk at the drawings f the labratry equipment in Figure 1 belw. In the chart that fllws, write the name f each piece f labratry equipment under the clumn titled Identify It. 2. Carefully inspect the different types f labratry equipment that have been set ut by yur teacher. In the space prvided, draw the item and recrd the functin f each piece f labratry equipment. Equipment Wrd Bank Evaprating Dish, Mrtar and Pestle, Test Tube Hlder, Aprn, Clay (Pipe stem) Triangle, Test Tube Rack, Ring Stand, Frceps, Stir Rd, Metric Ruler, Beaker, Graduated Cylinder, Pipette, Watch Glass, Funnel, Thermmeter, Erlenmeyer Flask, Scpula, Test Tube, Crucible, Beaker Tngs, Ring Clamp, Bunsen Burner, Wire Mesh with Ceramic Center Figure 1 A B C D E F

26 H I J K L G M N O P Q R S T U V W X Identify It (What is the piece f equipment called?) A. Erlenmeyer Flask Draw It (Draw/cut ut the picture f the tl) Explain It (What is the functin f the piece f equipment in specific, cmplete sentence) Measure, mix, and hld liquids in the lab. B.

27 C. D. E. F. G. H. I. J. K. L.

28 M. N. O. P. Q. R. S. T. U.

29 V. W. X.

30 Analysis and Cnclusins 1. Which labratry tls can be used t handle small bjects r chemicals? 2. Which labratry tls are useful when heating a liquid? 3. What tl r tls wuld yu use t make each f the fllwing measurements? What is the unit f measurement fr each tl? (Tls may r may nt be listed abve.) A. amunt f milk in a small glass: B. length f a maple leaf: C. temperature f the water in a lake: D. mass f a sea turtle: 4. Hw d labratry tls imprve the bservatins made by a scientist? Ging Further: Examine ther types f labratry equipment that yu will be using in the chemistry labratry. Try t determine the functin f each piece f equipment. Buret Crucible Tngs Flrence Flask Test tube clamp