Notes on Lessons 11-13
Notes on Lessons 11-13 CHMY 141N - 00
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This 5 page Class Notes was uploaded by Corymarie Notetaker on Friday October 2, 2015. The Class Notes belongs to CHMY 141N - 00 at University of Montana taught by Mark Cracolice (P) in Fall 2015. Since its upload, it has received 29 views. For similar materials see College Chemistry I in Chemistry at University of Montana.
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Date Created: 10/02/15
HMY m NOTES ssssssssss 13 lESSON ll How DO HEMISi WEIGH AND OUNi mums Then subscripT numbers in a chemical formula are used To i ndicaTe The number of aToms or groups of aToms of each elemenT in The formula uniT of The subsTance ATomic Mass The average mass of an elemenT39s aToms compared To The mass of a carbon12 aTom Formula Mass average mass of a compound based on The chemical formula for ThaT compound compared To The mass of an aTom of carbon12 o The formula mass of a compound is equal To The sum of all The aTomic masses in The formula uniT The subscripT indicaTes how many of each aTom as well as any coefficienTs Subscrist are indicaTion for only one elemenT in a chemical formula coefficienTs indicaTe The amounT for The elemenT or compound afTer iT Molecular Mass average mass of a molecular compound based on iTs chemical formula compared To The mass of an aTom of carbon12 O formula mass molecular mass buT molecular mass is noT always The formula mass Mole a number To describes The number of parTicles in a sample 0 one mole is The amounT of any subsTance ThaT conTains The same number of uniTs as The number of aToms in exachy 12 grams of carbon12 o 1 mole of any subsTance 602 X 1023 uniTs of ThaT subsTance Avogadro39s number named in honor of The man whose experimenTs wiTh gases led To The mole concepT o 602 X 1023 Molar mass The mass in grams of one mole of a subsTance o The bridge beTween The parTiculaTe and microscopic levels conversion facTor for calculaTions The molar mass of any given subsTance in grams per mole is numerically equal To The aTomic molecular or formula mass of ThaT subsTance in aTomic mass uniTsu if you have The aTomic or formula mass of a subsTance change The uniTs from u To gmol and you will have molar mass PercenT The amounT of one parT of a mixTure per 100 ToTal parTs in The mixTure O oA parTs AToTal parTs X 100 o The percenT composiTion of a compound is The percenT by mass of each elemenT in The compound Can puT The percenT of The elemenT in grams over 100 g of The compound for calculaTions The masses of all elemenTs in a compound and The mass of The compound iTself are direchy proporTional To each oTher lES SON 12 How ARE HEMIiAL lORMUlAS DETERMINED CombusTion analysis a Technique used To deTermine The formula of a compound a compound is burned for The purpose of analyzing iTs composiTion Empirical formulasimplesT formula O O To find The empirical formula of a compound you musT find The wholenumber raTio of aToms of The eemenTs in a sample of The compound How To find an empirical formula I find The masses of differenT elemenTs in a sample of The compound I converT The masses inTo moles of aToms of The differenT elemenTs I express The moles of aToms as The smallesT possible raTio of inTegers by dividing each moe number by The smallesT moe from above sTep I wriTe The empirical formula using The number for each aTom in The inTeger raTio as The subscripT in The formula percenTage composiTion figures represenT The grams of each elemenT in a lOOg sample of The compound To find The molecular formula of a compound O O O O deTermine The empirical formula of The compound calcuIaTe The molar mass of The empirical formula uniT deTermine The molar mass of The compound usually sTaTed in The problem divide The molar mass of The compound by The molar mass of The empirical formula uniT To geT n The number of empirical formula uniTs per molecule MulTiply The empirical formula by n wriTe The molecular formula lESSON ll How IS HEMIiAl HANGE EXPRESSED SYMBOLKAllYl A chemical change occurs when The chemical idenTiTy of a subsTance is desTroyed and a new subsTance is formed 0 can usually be deTecTed by one or more of our physical senses I Change in color I FormaTion of a solid when clear liquids combine I FormaTion of a gas indicaTed by bubbles coming from a liquid or a visible gas coming off The Top of The racTion I HeaT a producT or a reacTanT produces heaT in a reacTion or uses heaT in a reacTion Making iT hoT or cold I LighT chemicals reacTing To emiT lighT glow sTicks fire When a subsTance is dissolved in waTer The mixTure is an aqueous soluTion aq EquaTions are balanced by placing a coefficienT in fronT of one or more oT The formulas Once an equaTion is balanced iT is boTh a qualiTaTive and quanTiTaTive descripTion of The reacTion 0 only use coefficienTs To balance an equaTion Don T add any chemicals or change any formulas To make The equaTion balanced O qualiTaTive informaTion Tells you whaT reacTs To creaTe The producTs O quanTiTaTive i nformaTion how many molecules of each reacTanT reacT To produce however many molecules of The producT number of molecules deTermined by The coefficienT 0 molar i nTerpreTaTion of The chemical equaTion coefficienTs represenT how many moles of each subsTance are needed and reacT I molar mass gmol is The link To mass from moles in The equaTion represenTed by The coefficienT combusTion reacTion synThesis reacTion reacTion in which Two or more subsTances combine To form a single producT A X AX decomposiTion reacTion reacTion ThaT a compound breaks down To simpler subsTances AX A X singlereplacemenT reacTion reacTanTs are always an elemenT and a compound and The elemenT replaces The like elemenT meTalmeTal nonmeTal nonmeTal in The compound for The producT A BX AX B 0 an example is an oxidaTionreducTion reacTionredox reacTion burning oxidaTion reacTion elecTrons are Transferred from The carbonhydrogenoxygen compound To oxygen ReacTanTs are a compound of carbonhydrogenoxygen and oxygen gas producTs are CO2 and H20 doublereplacemenT reacTion soluTions of Two compounds are mixed and a precipiTaTe may form AX BY AY BX 0 an example is when an acid and base mix and neuTralize They creaTe a salT and waTer QUKK SiUDY AID grams Element Grams Moles Mole Ratio Formula Empirical moles of all elements Ratio Formula mo39e divided by the smallest mole Organization Chart for solving for Empirical Formula Molecular mass calculated mole 602 X 1023 Molar mass of compound Empirical Formula units In 1 Molecule molar mass of empirical formula Reactants Reaction Type Equation Type Products Any combination of elements and compounds that Combination A X AX one compound form one product two new compounds which may be a solid water Solution of two ionic compounds each with a positive Doublereplacement AX BY AY BX and negative ion acid or an aqueous ionic compound
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