Principles of Chemistry I
Principles of Chemistry I 004 011
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This 8 page Class Notes was uploaded by Bianka Hansen on Friday October 23, 2015. The Class Notes belongs to 004 011 at University of Iowa taught by Darrell Eyman in Fall. Since its upload, it has received 48 views. For similar materials see /class/228110/004-011-university-of-iowa in Chemistry at University of Iowa.
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Date Created: 10/23/15
I The Study of Chemistry I Classifications of Matter Ill Properties of Matter IV Units of Measurement V Uncertainty in Measurement VI Dimensional Analysis 1 The Study of Chemistry Chemistry the study of matter and its gragerties the changes that matter undergoes and the energy associated with these changesquot Understanding chemistry requires thinking at two levels macroscopic properties amp behavior we can see eg mass volume color flammability submicroscopic properties amp behavior we cannot see eg atoms molecules chemical bonds modern instruments can see these today 2 2 8 3 Classifications and Properties of Matter matter chemical property chemical change chemical reaction physical states of matter solid liquid and gas elements and compounds mix ures physical property physical change extensive properties dependent on sample size Examples mass volume intensive properties independent of sample size Examples temperature gas pressure density IS BLBM the textbook 29 review terms your respon bility 4 Units of Measurement in science it39s metric Systeme Internationale d Unite s SI units SI Base Units 7 of them length meter m mass kilogram kg time second s temperature keIVIn amount of substance mole mol electric current ampere A luminous intensity candela cd Note most unit names use lowercase letters Common Decimal Prelixes Used with SI Units pm x Pre x Word Conventona EXPWIW Symbol Notation WWquot tera T liillion l OOO OOO OOO OOO lgtltl 0 2 glga G billion l OOO OOO OOO lgtltl 09 mega M million l OO 00 lgtltl oS kilo k inousand l OOO xi 03 hecto n hundred loo leOZ deka da lo lgtltl 0 o i lgtltl 0 dec d te o i lgtltl 0quot cenli c hundredth 0 ol lgtltl 0392 milli m inousandln 0 col lgtltl 04 micro ll millionln o oooooi lgtltl 0 name n illionl o ooooooom lgtltl 0 3 pico p liillionln o oooooooooool lgtltl oquot2 lemlo l quadrillionln o ooooooooooooool lgtltl oquot5 Examgles of Some SI Derived Units volume cubic meter m3 velocity meter per second ms acceleration meter per second squared ms2 density mass per volume mV SI Derived Units with SEcial Names frequency hertz Hz 1s s39l force mass gtlt acceleration newton kilogram gtlt Leg 2 N second 5 6 Comparison of Temperature Scales A A A 373K T 7 100 C T 212 F T iWaterboils TE 39 E39E TE E gHowdowe jag E 3 jog convert I K 00 0F 8 93 g5 9 9 Eb 20 Eb 310Kg 370 C g 986 F Norrr1a1 body temperature 0 O O S S 2 273K i 0 C L 7 32 F L 3 Water freezes I M CK 27315 Fahrenheit scale Temperature Conversion 250 100 0c 212 F 200 a up 395 150 a c c 9 100 a S I I If 50 a straight line y mx b ooc 32 F 0 l l l l l 0 2O 4O 60 80 100 120 Celsius rise 212 32 9 g n 100 O or y intercept 32 9C 056 9F 32 8 Chem 4011 Previous Exam Question A UI student developed the Hawkeye temperature scale H She chose to make O OH equal to 25 C and each Hawkeye degree half the size of a Celsius degree What is the boiling point of water on the Hawkeye scale 5 Uncertainty in Measurement The number of significant figures in a measurement depends upon the measuring device 323390 Accuracy vs Precision accuracy nearness to the true value the bull s eye nearness to the other measurements precision systematic error a constant error that affects all measurements the same random error a variable error that affects each measurement differently 11 Significant Figures in Calculations The term significant figures refers to digits that were measured When rounding calculated numbers significant figures must be considered to avoid overstating the accuracy of answers All digits are significant except zeros that are used only to position the decimal point Make sure that the measured quantity has a decimal point Start at the left of the number and move right until you reach the first nonzero digit Count that digit and every digit to it s right as significant Zeros that end a number and lie either after or before the decimal point are significant thus 1030 mL has four significant figures and 5300 L has four significant figures Numbers such as 5300 L are assumed to only have 2 significant figures Aterminal decimal point is often used to clarify the situation but scientific notation is the best Rules for Significant Figures in Answers 1 For addition and subtraction The answer has the same number 12f decimaipimx ax there are in the mmmmm with thefewext decimatpimx Example adding two volumes 88 5 mL 28 28 mL 108 78 mL 1068 mL Example subtracting 1W0 Volumes 885 9 mL 7 2 8121 mL 888 0879 mL 8631 mL 2 For multiglication and division The number with the least certainly limits the certainty ol the result Therelore the answer with thefzwext xig gx 92 cmXB 8 cmX03744 cm 23 4225 cm323 Cma U General Notes on Significant Figures Keep a close eye on decimal points 340 has 3 sig figs but 340 has 2 sig figs Convert to scientific notation and drop insignificant zeros 000039600 39600 x 10quot has 5 sig figs Exact numbers eg 4 atoms have infinite sig figs Don39tround off until you are finished with calculations Ch 1 MasteringChemistry homework practice on sig figs Exercise How many significant figures in each of the following numbers or results a 1230 b 01234 c 1230 d 1230 e 24 gtlt 359 8616 f 1645 147 175 Rules for Rounding Off Numbers e rhan 5 the oreoedrng number rnoreeses roun s1o5 81Hhreesig two signi cant igures are retain 1 11 the drgu removed rs mor by 1 5 379 nihcanl ligures are retained and lo 5 4 11 ed 2 11 the drgn removed rs ess ha15 the oreoedrng number rs unchanged 0 2413 rounds to u 241 11 three srgnnroenl ligures are retained and lo 0 24 11 two srgmnoenl ligures are retained 3 11 the drgu removed rs 51ne oreoedrng number rnoreeses by 1 r1 r1 rs odd and remerns unchanged r1 r1 rs even rounds to 17 8 ul17 85 round 11 the 5rs1oiiowed only by zeros rule nonzeros rule 1 rs lollowed 7 8500 rounds to 17 8 but 17 8513 rounds to 17 7 s to 17 8 81s1ollowed the 51s1ollowed by two or more edduronei srgnnroenl1rgures1nrougn 3 Be sure to ca y mullislep calculation and round 011 only the rna answer ACommon Rounding Mistake Exercise Calculate and round correctly 06521 11 x 153 A 27 B 28 C 30 D none of the above 6 Dimensional Analysis a Veryuseful problem solving methodology also called the factorunit method or factorlabel method or factordimensional analysis handy for unit conversions eg mileshour to meterssecond conversion factors choose equalities ratios or factors that cancel out unwanted units leaVIng desired units Do not memorize reelpes Exercise My calculator weighs 192 grams Whatis its weight in pounds 1 pound exact 4536 grams not exact 4 s gt 1 d 45 6 grams an called conversion factorsquot Multiplying a quantity by 1 does not change its value 1b 192 04232804 lb ix 4536 5 ACommon Error Modifying Factors Exercise A ball39s volume is 106 cubic inches Whatis its volume in cubic centimeters 1 in exact 25400 cm exact a 269 cm3 b 174 cm3 c neither Exercise Expressed in scientific notation how many nanometers are in 589 centimeters 589 cm gtlt factor gtlt actor gtlt nm 1cm 10 2m 1nm 10 9m Problem Solving Density Densig 1 Density 2 adefinition or formula density w or d 3 volume V Exercise Whatis the density of magnesium if a 236 g sample has a volume of 136 mL 2 Density 2 an algebraic equation gtltV orV d 350 mL of ethanol d 0789 gmL is added to a beaker whose mass is 4928 g Whatis the mass of the beaker plus alcohol Solution Mock Quiz 1 Is a solid s surface area an intensive or extensive property 2 How many significant figures in each of these measurements a 1230gtlt1O393m b 001235 c 120039 3 Calculate and round 749 689 749 681 4 How many centimeters are in 107 km