Chem 101 test 1 notes - Exam 1 summary guide to study for - General Chemistry Lecture PDF

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Exam 1 summary guide to study for...

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CHEM%101% % % % % % % 05/31/16% % Chapter%1:%% % Units&of&Measurement& • SI%Units:% o Uses%a%base%unit%for%each%quantity% o Base%units%for%all%other%units% -We%consider%the%base%units%for:% • Length%in%meter%(m)% • Mass%in%kilogram%(kg)%*The%amt%of%material%in%an%object% • Temperature%in%kelvin%(K)%*%measure%of%hotness%or%coldness%in%an%object% % Prefixes:%Used%to%indicate%the%fractions%or%multiples%of%various%units% • Convert%the%base%units%into%units%appropriate%for%item%being%measured% Ex:%Milli-%a%10-3%fraction%=%one%thousandth%of%a%unit% Ex:1%millimeter%(mm)%is%10-3%meter%m)% 1mm=1x10-3%m% 1kg=1000g% % *If%something%is%exact,%there%is%uncertainty%associated%with%it% *Every%prefix%is%related%back%to%its%base%unit% % Derived&SI&Units:& • Volume-%most%commonly%used%units% • M3%or%cm3%%(used%for%solids)% o Cube:%L%x%W%x%H% • Liter%(L),%Milliliter%(mL)%(used%for%liquids)% o 1mL=1cm3%(Direct%relationship)% • Density:%amount%of%mass%in%a%unit%volume%of%a%substance% o g/cm3%or%g/mL% o Temperature%Dependent%(Density=mass/volume;%d=m/v)% o Density%of%Water:%1.00%g/cm3%when%iced,%volume%expands%so%density% becomes%smaller.%Therefore,%ice%floats%in%water,%since%less%dense%than% water)% % Dimensional&Analysis& • Dimensional%analysis:%procedure%of%changing%units%to%ensure%to%get%the% proper%unit%using%conversion%factors% o Conversion%Factor:%A%fraction%with%numerator%and%denominator%the% same%quantity%but%different%units% § Given%unit%x%%(Desired%unit/Given%unit)%=%Desired%unit% § *Given%units%cancel%out)% • Converting%from%one%unit%to%another%for%the%same%measure% o 1%inch=2.54%cm%

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Two%conversion%factors:%1in/2.54cm%or%2.54cm/1in% Example:%20.2%in%to%cm?% • (20.2%in)%(2.54cm/1in)=51.3cm%*Need%inch%in% denominator%to%cancel%out%with%the%20.2%INCH% • Or%(20.3in)%(1in/2.54cm)=7.95in2/cm%(Wrong%method)% **We%never%start%with%the%conversion%factor!%Always%start%with%the%number%that%has% one%unit% % Example:%How%many%centimeters%are%there%in%6.51%miles?%Mi->cm% • 1mi=5280ft% 1ft=12in% 1in=2.54cm% • %*Set%up%in%a%way%which%units%cancel%out% 6.51mi%(5280ft/1mi)%(12in/1ft)%(2.54cm/1in)%=1047682944cm% 3%SFs%%%%%%%%%exact%%%%%%%%%%%%%%%%exact% exact% %%%%%%%%%%%%%=1050000cm% % % % % % % % =1.05%x%106%cm% % % % % % % % =3%SFs% • Anything%that%comes%from%measurement%is%not%exact,%so%need%to%count%sig% figs)% % Example:%A%bucket%contains%4.65%L%water.%How%many%gallons%of%water%is%that?% • 1L=1.057qt% 1gal=4qt% 4.65L%(1.057qt/1L)%(1gal/4qt)%=1.23%gal% 3SFs% %%4SFs% % exact%% % 3%SFs% *GO%with%the%fewer%sig%figs%(whichever%relationship%is%not%exact;%memorize% chart;%use%sig%figs)% % Example:%Convert%1.36%x%109%km3%to%liters%%%%Km3%->%L% • 1L=10-3%m3% 1km=103m4% • 1.36%x%109%km3%%%%(103m/1km)(1L/10-3m3)%=1.36%x%1021%L% • Raise%conversion%factor%to%same%factor:%(103m/1km)3%=%109m3% • Km3% % Example:%The%volume%of%well%is%40.0%ft3.%How%many%kilograms%of%concrete%will%it%take% to%fill%the%well%if%the%density%of%concrete%is%2.85%g/cm3?% *Never%start%our%equation%with%the%conversion%factor!% *1kg=1000g% Ft3%->%kg%%(*Due%to%uncertainty%from%measurement,%determine%sig%figs)% % 40.0%ft3%%(12in/1ft)3%(2.54cm/1in)3%(2.85g/1cm3)%(1kg/1000g)%=%3228.12kg%% *We%use%3%sig%figs%so%final%answer%is:%3230%kg%or%3.23%x%103%kg% % Relationship%between%a%prefix%and%a%base%unit:%1kg=1000g%->%example%of%an%exact% relationship% % Chapter&2:&Atoms,&Molecules,&and&Ions& & Structures&of&Atoms&

-An%atom%consists%of%a%positively%charged%nucleus%surrounded%by%one%or%more% negatively%charged%particles%called%electrons.% -Every%atom%is%composed%of%3%subatomic%particles:% • Proton:%Positive%(1+)=%1.0073%amu% • Neutron:%Neutral%(none)=%1.0087%amu% • Electrons%Negative%(-1)=%5.486%x%10-4%amu% *amu=%atomic%mass%unit% 1%amu=1.66054%x%10-24%g% *Neutron%and%proton%inside%nucleolus% *Mass%is%in%the%nucleolus% *%An%atom%has%no%electrical%charge% % Atomic&Number,&X:%The%number%of%protons% -Because%an%atom%has%no%charge,%#%electron%must%be%equal%to%#%of%proton% -Thus,%number%of%electron%in%a%neutral%atom% -It%specifies%an%atom% % Mass&Number,&A:%Number%of%Protons%and%Number%of%Neutrons%for%a%specific%atom%% % ! %X% (X=%atomic%symbol)% ! % • Elements%are%symbolized%by%one%or%two%letters% o Second%letter%lower%case% % !"# Example:%Determine%the%number%of%protons,%Neutrons,%and%Electrons%in% !" Ag?% • • •

Mass%number:%107% Atomic%number%is%47%(#%of%proton=47%and%#%of%electron=47)% #%of%Neutrons:%107-47=60%

% Isotopes:%Atoms%of%the%same%element%with%equal%number%of%protons,%different% number%of%neutrons% • Different%Mass%number% • Most%elements%have%several%naturally%occurring%isotopes% • Different%abundance% Example:%Boron%has%2%isotopes% !! !" % B%% % 𝐵% ! ! % p=5%%%%%%%%p=5% % n=6%%%%%%%%n=5% % 80.22%%19.78%% -Different%elements%have%different%number%of%isotopes% !! !" Ex:% C%%%% 𝐶% !

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%%%%N=5%%%%%%%%n=6% %

Atomic&Weight,&AW:%the%total%masses%of%all%the%isotopes%of%an%element%considering% their%relative%abundances% % -Also%called%Average%Atomic%Mass% Atomic%Weight=%𝜀 [(isotope%mass)(%%isotope%abundance)]% % Example:%Naturally%occurring%chlorine%is%75.78%%35Cl%(atomic%mass%34.969%amu)%and% 24.22%%37Cl%(atomic%mass%36.966%amu).%Calculate%the%atomic%weight%of%chlorine.% % 35Cl%Abundance=75.78%% % Atomic%Mass=34.969%amu% 37Cl%Abundance=24.22%% Atomic%mass=36.966%amu% % *Using%the%atomic%weight%formula:%% Atomic%Weight=%𝜀 [(isotope%mass)(%%isotope%abundance)]% AW=%(34.969amu)(0.7578)%+%(36.966amu)(0.2422)% =26.50amu%+8.953amu%%%%*Write%as%a%decimal!% =35.45amu%%%*For%addition%&%subtraction,%less%digits%after%decimal%counts%in%sig%figs% % % *For%multiplication%&%division,%less%sig%figs% % PERIODIC%TABLE:% • Elements%arranged%in%order%of%increasing%atomic%number% • Each%horizontal%row%is%a%period% • Elements%with%similar%properties%placed%in%vertical%columns,%called%groups% st 1 %group%is%alkaline%metal% 2nd%group%is%alkaline%earth%metal% Middle:%Transition%metal% *8%main%groups.%(Elements%in%same%group%share%similar%properties)% *Elements%on%the%left%of%the%step-like%line,%metals% • With%the%exception%of%Hydrogen% *Elements%on%the%right%of%the%step-like%line,%nonmetals,%and%Hydrogen%(mostly%gas% and%soft%metals)% *Elements%on%the%borderline%of%step-like%line,%metalloids% • With%the%exception%of%Al%%(Depending%on%which%side%of%the%line%it%will%touch,%it% will%act%either%like%a%metal%or%non-metal)%% • Aluminum=metal% % MOLECULES%&%CHEMICAL%FORMULAS:% -Molecular%compounds:%Composed%of%molecules%containing%more%than%one%type%of% atoms%%%%H2O%%%%CO2% -Chemical%formula:%Gives%the%composition%of%each%substance%by%letters%and%numbers% a. Molecular%formula:%Gives%the%actual%number%of%atoms%in%a%molecule% *Hydrogen%peroxide:%H2O2%% Calcium%Nitrate:%Ca(NO3)2%%%%% (1Ca%atom,%2%N%atoms,%6%O%atoms)% b. Empirical%formula:%Gives%the%simplest%ratio%of%atoms%in%a%molecule%

*Hydrogen%peroxide:%HO%% Calcium%Nitrate:%Ca(NO3)2%%%%% % % NAMING%CHEMICALS:% Organic%Compounds:%Contain%carbon%and%hydrogen,%often%with%oxygen,%nitrogen% or%other%elements% Inorganic%Compounds:%All%others:% • Ionic:%Metal%and%nonmetal:%KBr% • Molecular:%Only%nonmetal:%SO2% o Diatomic:%Molecular%compound%made%of%two%identical%atoms:% § %Br2%H2% • Acids:%Contain%and%begin%with%hydrogen:%HNO3% % % IONS%AND%IONIC%COMPOUNDS:% • Ions:%formed%when%an%atom%gains%or%loses%electrons% o Cations:%A%metal%atom%lost%electrons%resulting%in%an%ion%with%positive% charge:%Ca2+,%Na+% o Anion:%A%nonmetal%atom%gained%electrons%resulting%in%an%ion%with% negative%charge:%O2% • Ionic%Compounds:%Combinations%of%metals%and%nonmetals”%CaF2,%Na2O% • How%many%electrons%does%Na+%have?% o 10%(because%Z%(atomic%#)%=11%->%11%protons%and%positive%charge% means%it%lost%an%electron.%So%11-1=10%electrons%% % % NAMING%CATION:% 1)%Cations%formed%from%metal%atoms%forming%cation%with%one%fixed%charged% -Have%the%same%name%as%the%metal% -Group%1A%and%2A%and%3A%metals%with%charge%equal%to%group%number% -Two%Transition%metal:%Zn2+,%Ag+% %%%%%Na+:%Sodium%ion%%%%Mg2+:%Magnesium%ion%%%%%Zn2+:%Zinc%ion% % 2)%Cations%formed%from%metal%atoms%forming%cations%with%different%charges:% -The%positive%charge%is%indicated%by%a%Roman%numeral%in%parentheses%following%the% name%of%the%metal% -Mostly%transition%metals%in%the%middle%of%periodic%table% %%%%%%%%%%Fe2+%iron%(II)%ion%%%Cu+%Copper%(I)%ion% % 3)%Cations%formed%from%nometals:% -Have%names%that%end%in%–ium% NH4+%ammonium%ion% H3O+%hydronium&ion& & Naming%Anions%:% %Monatomic&atoms:&The%ending%of%the%name%of%the%element%is%replaced%with%–ide%

• H-%hydride%ion% • N3-%Nitride%ion% • O2-%Oxide%ion% *A%few%polyatomic%anions%have%names%ending%in%–ide% % O2-%peroxide%ion% % OH-%hydroxide%ion% % CN-%Cyanide%ion% % Group%5A%is%3-% Group%6A%is%2-% Group%7A%is%1-% % 2.%Polyatomic%anions%containing%oxygen,%oxyanion:%Have%names%ending%in%–ate%or%– ite.% • Oxyanions%involving%the%same%element% • NO3-%Nitrate%ion-more%oxygen% • NO2-%Nitrite%ion-less%oxygen% • SO42-%Sulfate%ion-more%oxygen% • SO32-%Sulfite%ion-less%oxygen% % *Pre-fixes%per,%hypo%used%for%oxyanions%extending%to%4%members.% • Per:%indicates%one%more%O%atoms%than%the%one%ending%in%–ate% • Hypo:%indicates%one%fewer%O%atom%that%the%one%ending%in%–ite% ClO4-%perchlorate%ion%(one%more%O%than%chlorate)% ClO3-%chlorate%ion% ClO2-%Chlorite%ion%(one%O%fewer%than%chlorate)% ClO-%hypochlorite%ion%(one%O%fewer%than%chlorite)% *Same%rule%applies%to%bromine%since%it%is%the%same%group.% % 3.%Anions%derived%by%adding%H+%to%an%oxyanion:%Add%prefixes%hydrogen%or% dihydrogen% CO32-%carbonate%ion% HCO3-%%hydrogen%carbonate%ion% ***Memorize%the%common%anion%chart% % Naming%Ionic%Compounds:% • Cation%name%followed%by%anion%name% o Name%from%left%to%right% o First%name%remains%unchanged% o Second%name%altered% BaCl2%–%Barium%chloride% Al(NO3)3%Aluminum%Nitrate% % Example:%Name%the%following%compounds%Cu(ClO4)2%

*First%thing%you%see%is%metal%so%it’s%ionic.%->%cation:%copper%ion%*forms%cation%with% different%charges% (ionic%compound%has%one%cation%and%one%anion)% è Anion%is%a%polyatomic:%ClO4-%% Determine%the%charges:%Compound%must%be%neutral% è 1(Cu)%+%2(-1)=0%%(*Cu%is%the%unknown:%x)% è Cu=+2%->%Copper%(II)%perchlorate% % Example:%CaCl2%%(Ionic%compound%since%Ca%is%metal)% Cation:%calcium%ion,%group%2,%fixed%charge%2+% Anion:%Cl-,%monatomic,%ide% è Calcium%Chloride% % Example:%NH4NO3%%% Cation:%NH4+%ammonium%ion%% Anion:%NO3-%% Ammonium%Nitrate% % Writing&Chemical&Formulas&for&Ionic&Compounds& 1.%First%cation,%then%anion% 2.%Determine%charges%after%determining%if%it%is%ionic%or%not.% è Charges%are%not%written%in%a%formula% è Overall%electrically%neutral,%total%positive%charge%must%equal%total%negative% charge% 3.%Trade%Charges% Magnesium%Chloride:%Mg2+%and%Cl-%becomes%MgCl2% Sodium%Chloride:%Na++%and%Cl-%becomes%NaCl% *Trading%charges%are%not%necessary%if%the%charges%are%eqal.%% è Use%the%lowest%ration%of%ions% o Write%as%an%empirical%formula% § Ca2+%and%S2-%becomes%Ca2S2%->%CaS% % Example:%Give%the%chemical%formula%for%each%of%the%following%compounds:% a.%Zinc%Nitrate% *Groups%1-3%have%fixed%charges%so%Zinc%is%fxed.%% *Ending%determine%whether%its%monatomic%or%polyatomic.%–ate%is%polyatomic,%-1% charge.% è Zn2+%%%%%NO3-% è Zn(NO3)2%%%%*Polyatomic%ion%in%parenthesis% % b.%Iron(III)%nitride%%%%%*Roman%numeral%shows%the%charge% Fe3+%% N3-%%->%Fe3N3%->%FeN% % c.%Iron%(III)%Carbonate% Fe3+%%%CO32-% Fe2(CO3)3%

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d.%Alumnium%Hydoxide% Al3+%%%%%OH-% Al(OH)3% Example:%What%is%the%charge%of%Fe%in%FeSO4?% Fe?%%SO42-% 1(Fe)%+%1(-2)=0% Fe=%+2%% *They%also%trade%the%charges%so%Fe%must%be%2%so%they%cancel%with%the%2-% % Naming&Binary&Molecular&Compounds& è Made%of%Two%nonmetals% è First%element%farthest%to%the%left%in%periodic%table,%exception:%Oxygen%always% last%unless%combined%with%fluorine% è Second,%element%is%given%an%–ide%ending% è Greek%prefixes%to%indicate%the%number%of%atoms% è Prefix%mono%never%used%with%the%first%element% Ex:%NF3%Nitrogen%trifluride%%%(First%name%unchanged)% %Don’t%need%to%say%mono%when%theres%only%one%nitrogen.% 3%F%so%prefix%is%–ide%% % è If%prefix%ends%in%a%or%o%and%the%name%of%second%element%begins%with%a%vowel,% drop%the%a%or%o%of%the%prefix% o CO%carbon%monoxide% Example:%Give%the%name%or%molecular%formula% Sulfur%dioxide%->%SO2% BrF3%Bromine%trifluride% PCl5%Phosphorus%pentachloride% N2O5%Dinitrogen%pentaoxide% *Always%–ide%for%molecular%compounds% % Diatomic&Molecules& -These%seven%elements%occur%naturally%as%molecules%containing%two%atoms:% % H2,%N2,%O2,%F2,%Cl2,%Br2,%I2% Are%gases% -Acids:%are%molecular%compounds%made%of%nometals% % Start%with%hydrogen% % Composed%of%anion%and%% *more%notes%on%slide% Anions%end%in%–ide:%add%prefix%hydro%and%replace%ide%with%ic%followed%by%word%acid% Ex:%Chloride,%Cl-%->%hydrochloric%acid,%HCl% è Anions%end%in%–ate:%replace%ate%with%ic% è Chlorate,%ClO3-%->%Chloric%Acid,%HClO3% è Anions%end%in%ite:%replace%ite%with%ous% è Chlorite,%ClO2-%->%Chlorous%acid,%HClO2% Prefixes%in%the%anion%names%are%retained%in%the%name%of%the%acid%

è Perchlorate,%ClO4-%->%Perchloric%acid,%HClO4% è Hypochlorite,%ClO-%->%Hypochlorous%acid,%HClO% Example:%Name%the%following%acids%% è H2S%:%monatomic%anion%S2-,%Sulfide% o Hydosulfuric%acid,%H2S% % Forming&Acids:& Charges%are%used%when%forming%acids%since%they%act%like%ionic%compounds% è Sulfuric%Acid% H+%%%%SO42-%%->%H2SO4% Example:%Give%the%chemical%formula%for%each%of%the%following%compounds:% 1)%Potassium%Sulfate:%K+%SO42-%%->%K2SO4% 2)%Dinitrogen%hexasulfide:%NsS6%%->%NS3% 3)%NH3:%Nitrogen%trihydride%->%ammonia% 4)%H2O:%dihydrogen%monoxide%->%water% % Chapter%3:%Chemical%Reactions%and%Reaction%Stoichiometry% è Chemical%Reactions:%Process%where%one%or%more%substances%are%transformed% into%one%or%more%different%substances% o Changes%that%occur%during%a%chemical%rxn% Ø Chemical%equations:%symbolic%representation%of%a%chemical%reaction% o 2H2%(g)%+%O2%(g)%->%2H2O%(l)% Reactants% % Products% Reactants:%Starting%chemicals% Products:%Ending%chemicals% Coefficients:%Represents%the%amount% % -Coefficient%1%usually%not%written% Phases:%State%of%the%chemicals%(aq;%dissolved%in%water,%s,%l,%g)% *Coefficients%tell%the%number%of%molecules% *Subscripts%tell%the%number%of%atoms%of%each%element%in%a%molecule% % Balancing%Chemical%Equations:%having%equal%number%of%each%element%on%both% reactant%and%product%sides%by%changing%the%coefficients% Ø 2H2%+%O2%->%2H2O% 2x2=4%H% 2x2=4% 1x2=2%O% 2x1=2%O% 1.%Write%reactants%and%products% 2.%Select%coefficients%that%will%make%the%number%of%each%element%equal%on%both%sides% % -Identify%the%most%complex%substance;%assume%the%final%equation%has% one%molecule%of%it% % -Start%with%the%element%appears%the%least% 3.%Use%smallest%whole%numbers% Example:%Balance%the%following%equation:% Mg(NO3)2&(s)&+&Li&(s)&->&Mg&(s)&+&LiNO3&(s)& Mg:1% % % % % Mg:1% NO3:%2%% % % % NO3:%1%->%2% Li:1% % % % % Li:1%

% % % Example:%Write%the%balanced%equation%when%aqueous%silver%nitrate%reacts%with% aqueous%calcium%chloride%to%produce%solid%silver%chloride%and%aqueous%calcium% nitrate% *Silver:%transition%metal% Ag+%NO3-1%+%Ca2+Cl-1%%->%%Ag+Cl-1%+%Ca2+NO3-1% AgNO3%(aq)%+%CaCl2%(aq)%->%AgCl%(s)%+%Ca(NO3)2%(aq)% Ag:%1%->%2% % % Ag:%1%->%2% NO3:%1->%2% % % NO3:%2% Ca:%1% % % % Ca:%1% Cl:%1% % % % Cl:1%->%2% % Types%of%Chemical%Reactions:% Ø In%the%chapter:% 1.&Combination&Reactions:%Two%or%more%chemicals%react%to%form%one%product% • If%a%metal%and%a%nonmetal%combine,%product%is%ionic% o X+Y%->%XY% o 4Fe%(s)%+3O2%(g)%->%2Fe2O3%(s)% o N2%(g)%+%3H2%(g)%->%2NH3%(g)% Example:%When%Mg%and%N2%undergo%a%combination%reaction,%what%is%the%chemical% formula%of%the%product?% • Mg(s)%+%N2(g)%->%Mg2+N3-% • Mg(s)%+%N2(g)%->%Mg3N2% • 3Mg(s)%+%N2(g)%->%Mg3N2% 2.&Decomposition&Reactions:%One%chemical%reacts%to%produce%two%or%more% products% • In%their%elemental%state% • XY%->%X%+%Y% • 2NH3(g)%->%N2(g)%+%3H2(g)% Balance%the%following%decomposition%reaction:% % 2N2O5(g)&->&NO2(g)&+&O2(g)& & O:%5% % 4% 2%%%=%6% % O:%10% % 8% 2%%%=10% Balanced%equation:%2N2O5(g)&->&4NO2(g)&+&O2(g)& Ø Example:%Write%the%decomposition%of%reaction%of%solid%sodium%nitride.% Sodium%nitride:%Na+N3-%% % % Na3N% • Na3N(s)%->%Na(s)%+%N2(g)%% • 2Na3N(s)%->%3Na(s)%+%1/2N2(g)%% • 2Na3N(s)%->%6Na(s)%+%N2(g)% 3.%Combustion&Reactions:&or%Burning,%hydrocarbons%reacting%with%O2% • Produces%a%flame% • Generates%CO2%and%H2O%

• H2O%can%be%liquid%or%gas,%H2O(g)%formed%at%high%temperature% Hydrocarbons%+%O2(g)%->%CO2(g)%+%H2O%(g%or%l)% ***Hydrocarbons:%compounds%containing%C%and%H% Example:%Write%the%balanced%equation%for%the%reaction%that%occur%when%ethanol,% C2H5OH,%burns%the%air?% • C2H5OH%(l)%+%O2(g)%->%CO2(g)%+%H2O(g)% • C2H5OH%(l)%+%O2(g)%->%2CO2(g)%+%3H2O(g)% • C2H5OH%(l)%+%3O2(g)%->%2CO2(g)%+%3H2O(g)% First%element%that%appears%only%once%in%most%complex%molecule%is%C% *Start%with%C% Example:%Write%the%balanced%equation%for%the%reaction%that%occur%when%isooctane,% C8H18,%burns%the%air?% % C8H18(l)%+%O2(g)%->%CO2(g)%+%H2O(g)% • C8H18(l)%+%25O2(g)%->%8CO2(g)%+%9H2O(g)% • 16O%+%9O=25O% Eliminate%the%fraction%by%multiplying%each%side%by%2% • 2C8H18(l)%+%25O2(g)%->%16CO2(g)%+%18H2O(g)% % Group%1:%1+% Group%2:%2+% *Middle:%transition%metals% Group%3:%3+% Group%4:%3-% Group%5:%2-% Group%6:%2-% Group%7:%1-% % Molecular&and&Formula&Weights:& Molecular%Weight,%MW:%the%sum%of%the%atomic%weights%of%all%the%elements%in%one% molecule% -Also%called%formula%weight%(FW),%or%Molecular%Mass%or%Formula%Mass% -Unit:%amu% Molecular%weight%of%H2SO4%:% % 2(AW%of%H)%+%(AW%of%S)%+%4%(AW%of%O)=% % 2(1.008)%+%32.07%+%4(16.00)=98.09%amu% % Avogadro’s&number&and&the&mole:& -Mole:%(mol)%is%a%unit%of%mater%that%represents%a%known%number%of%particles%large% enough%to%be%weighed%on%a%laboratory%balance% -One%mole%of%substance%contains%6.002%x%1023%molecules,%atoms,%or%ions% -%6.002%x%1023%is%called%the%Avogadro’s%number,%NA% -The%mole%is%just%a%number%of%things:% • 1%mole=6.022%x%1023%things% -Correct%name%for%a%particle%of%a%substance%is%based%on%the%type%of%the%substance% • Atom:%representative%particlelk%for%an%element%(ex:%Fe,%S)%

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Molecule:%representative%particle%for%a%compound%(Molecular,%Ionic,%Acids,% Diatomic)%(ex:%Co2,%KCl)% • Ion:%representative%particle%for%a%charge%particle%(ex:%Na+1,%Cl-1)% Example:%How%many%oxygen%atoms%are%there%in%4.0%x%10%23%molecules%of%perchloric% acid?% H+%% ClO4-% %%%%HClO4% ! ! !"#$% 4.0%x%1023%molecule%HClO4%(! !"#$%&#$ !"#$!)%=%1.6%x%1024%atom% % % Example:%How%many%oxygen%atoms%are%there%in%0.350%mol%of%S2O3?%(2%nonmetals%so% molecular)% !.!"" ! !"#$ !"#$%&#$' !!!! ! ! !"#$% 0.350%mols%%S2O3%( )%( )%=%6.32%x%1023%O%atoms% ! !"# !!!! ! !"#$%&#$' !!!! % Molar%Mass,%Mm:%mass%in%grams%of%one%mole%of%a%substance% • Numerically%equal%to%formula%weight% • Unit:%grams/mol% • Find%in%amu,%express%in%g/mol% 1%molecule:%18.0%amu%%->%(Avogadro’s%number)%1%mol=18%g/mol% Molar%Mass%of%H2SO4:%2%(1.008)%+%32.07%+%4(16.00)=98.09%g/mol% Molar%mass%is%a%conversion%factor%(grams/molecules)% % Example:%Calculate%(a)%the%number%of%moles%and%(b)%the%number%of%molecules%in% 35.00g%ethylene%glycol,%HOCH2CH2OH% Hint:%Use%the%molecular%formula%of%the%compound%to%calculate%its%molar%mass%in% grams%per%mole% a.%Mm%of%ethylene%glycole:%(2C)(12.01)%+%(6H)(1.008)%+%(2O)(16.00)=62.07%g/mol% ! !"#$ !!!!!! • 35.00g%C2H6O2%(!".!"! !!!!!! )%=%0.5639%C2H6O2% b.%The%number%of%molecules:%% 0.5639%C2H6O2%(6.022%x%1023%moleculesC2H6O2/%1%mole%C2H6O2)=3.396%x%10^23% molecules%C2H6O2)% % Example:%Calculate%the%mass%in%grams%of%0.433%mol%calcium%nitrate% Ca2+%No3-%%%Ca(NO3)2% Mm%of%calcium%nitrate:%(1Ca)(40.08)%+%(2N)(14.01)%+%(6%O)(16.00)=164.1%g/mol% • 0.433%mol%%Ca(NO3)2%(164.1%g%Ca(NO3)2/%1%mole%Ca(NO3)2)%% =%71.1%g%Ca(NO3)2% % Using%Moles:% Grams%%% *finish%copying%notes% % Percent&Composition:& Percent%Composition:%percentage%by%mass%contributed%by%each%element%in%a% compound%

Ø Chemical%compound%always%contain%the%same%proportions%of%element%by% mass% Ø Knowing%the%chemical%formula% %%Composition%of%element:%[(Number%of%atoms)(AW%of%element)]%/%(FW%of% substance)%x%100%% % Example:%Calculate%the%percent%by%mass%of%each%element%in%Al2O3% % %%Composition%of%element:%[(Number%of%atoms)(AW%of%element)]%/%(FW%of% substance)%x%100% FW=(2)(26.98)%+%(3)(16.00)=%101.96%amu% %%Al=%[((2)(26.98))/101.96amu]%x%100%=%52.92%%Al% %%O%=%[((3)(1...