CHEM 161: Final Exam Study Guide

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1 CHEM 161: Final Exam Study Guide Chapter 1 Scientific methd Knw the terms: macrscpic, micrscpic, atmic r mlecular level Significant Figures (Sig Figs) Scientific ntatin Prblem slving by unit analysis methd Metric system - Knw all prefixes frm femt t tera - Carry ut metric-metric cnversins - 1 cm 3 1 ml and 1 dm 3 1 L Length, mass, weight, vlume Vlume by displacement density = mass vlume - Be able t determine density, mass, r vlume given the ther tw quantities Temperature: cnvert F-t/frm- C and K-t/frm- C Percentage: rati f parts per 100 parts - Calculate the percentage r use a given percentage t calculate part r whle Classificatin f matter: Classify substances as elements, cmpunds, and mixtures Physical states f matter - Determine physical state f substances (slids, liquids, gases) with descriptins f vlume, shape, cmpressibility, attractin between particles, etc. - Knw terms fr transitin frm ne physical state t anther (e.g. freezing, cndensing, vaprizing, sublimatin, depsitin, etc.) Given examples r mlecular-level images, identify elements, cmpunds, and mixtures, as well as slids, liquids, and gases. Classify prperties and changes as physical r chemical. Chapter 2 KNOW peple and discveries assciated with: Jhn Daltn s Mdel Rutherfrd s Alpha Scattering Experiment Discvery f prtns, neutrns, electrns Use law f cnservatin f mass t slve prblems Subatmic particles prtn (p + ): +1 charge, inside nucleus, ~1 amu neutrn (n): neutral, inside nucleus, ~1 amu electrn (e ): 1 charge, ut f nucleus, 0 amu Mass number, atmic number, element symbl - Given 2, be able t determine the missing inf Recgnize the term istpe Atmic Ntatin (r Nuclear Symbl): mass number = atmic number Z A E = element symbl Determine the # f prtns, neutrns, and electrns given any istpe f an atm r in Peridic Table: - Knw terms: grups, perids, Main-grup (Representative) elements, transitin metals - Grup IA: alkali metals - Grup IIA: alkaline earth metals - Grup VIIA: halgens - Grup VIIIA: nble gases peridic law: Elements are rganized in the Peridic Table s thse with similar prperties belng t the same grup Metals, nnmetals, and semimetals: - Lcatin n Peridic Table and prperties Knw which elements are slids, liquids, gases at rm temperature (25 C) Knw which elements exist as diatmic mlecules at 25 C (H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2 ) mlecule: cmpund f 2 r mre nnmetals held tgether by cvalent bnds inic cmpund: cnsists f metal + nnmetal(s) frmula unit indicates rati f ins present CHEM 161 Final Exam Study Guide page 1 f 9

2 Chapter 2 (Cntinued) Knw the names and symbls f the first 18 elements f the Peridic Table, all elements n Fig n p. 59, and U. Crrect spelling f element names cunts! KNOW all f names and symbls fr the POLYATOMIC IONS Nmenclature: Identify a cmpund as inic r mlecular Given frmula f a cmpund, determine name. Given name f a cmpund, determine frmula. Mlecule r Mlecular Cmpunds: all nnmetals Use Greek prefixes when mre than ne Knw ammnia, methane, hydrgen perxide Inic Cmpunds: metal + nnmetal(s) ins catin(s) and anin(s) with verall charge f zer Determine the charges n Main-Grup elements using the Peridic Table Use charges n anins t determine charges n metals that can multiple charges. have high melting pints, all slids at 25 C Acids: Have H in frnt, physical state is (aq) Be able t name acids given the frmula r determine the frmula given the name. Chapter 3 Atmic Mass Knw that atmic weights reprted n peridic table are the weighted average f naturally ccurring istpes Mlar Masses Calculate mlar mass f element r cmpund 1 mle = Avgadr's # = units Mle Cnversins Cnvert amng masses, mlar mass, mles, mlecules, atms Percent Cmpsitin (r Mass Percentages) Calculate the percent by mass f each element in a cmpund Empirical and Mlecular Frmulas Knw empirical frmulas are simplest, whlenumber rati f atms. Determine empirical frmula given elemental analysis data Determine the mlecular frmula given the empirical frmula and mlecular weight Balancing Chemical Equatins 1. Balance metals. 2. Balance plyatmic ins Keep as ne unit. 3. Balance hydrgens. 4. Balance carbns. 5. Balance xygens. 6. Balance all ther atms. Interpreting Chemical Equatins reactants and prducts (s), (l), (g), and (aq) Cefficients give mle rati as well rati f elements and cmpunds Stichimetry: Calculatins invlving amunts f reactants and prducts in a chemical reactin cefficients in balanced equatin give mle ratis Mle-mle relatinships Mass-mass relatinships Limiting Reagent Prblems Calculate the mass r vlume f prduct made given amunt f reactants and chemical equatin Smallest amunt f prduct = amunt prduced Reactant prducing smallest = limiting reagent All ther reactants = reactants in excess Calculate the amunt f reactant in excess that remains after the reactin Yields f Reactins theretical yield: amunt f prduct predicted by balanced equatin when limiting reagent is used up actual yield: amunt f prduct ne actually gets Percent yield = actual yield theretical yield 100% CHEM 161 Final Exam Study Guide page 2 f 9

3 Chapter 4 Aqueus Slutins: liquid r slid slute in H 2 O slutin: mixture f 2 r mre substances slute: substance present in smaller amunt slvent: substance present in larger amunt KNOW the Slubility Rules these will nt be prvided n the ACS Exam! Predict prducts f a reactin given reactants fr Precipitatin Reactins precipitate (ppt): slid frming frm 2 slutins Acid-Base Neutralizatin Reactins HX + MOH water + salt HX + MHCO 3 water + CO 2 + salt HX + MCO 3 water + CO 2 + salt Oxidatin-Reductin (Redx) Reactins Cmbinatin reactin metal + nnmetal inic cmpd (s) Single-replacement reactins Given Activity Series slid metal + metal slutin slid metal + acid active metal + H 2 O (l) Cmbustin reactin C x H y + O 2 CO 2 (g) + H 2 O (g) C x H y O z + O 2 CO 2 (g) + H 2 O (g) Knw Arrhenius and Brnsted-Lwry (B-L) definitins fr acids and bases Electrlyte: substance that disslves in water t prduce ins that cnduct electricity strng electrlyte: breaks up cmpletely many ins present t cnduct electricity e.g. strng acids & bases, aqueus salts weak electrlyte: breaks up t small degree nly a few ins present t cnduct electricity e.g. weak acids & bases, insluble salts nnelectrlyte: a mlecular cmpund that frms mlecules in water (e.g sugar) n ins des nt cnduct electricity Acids and Bases as electrlytes Knw strng acids and strng bases! All ther acids and bases are weak Recgnize strng acids and bases inize cmpletely while weak acids and bases dn t Chemical Equatins and (Net) Inic Equatins Chemical Equatin: cmpunds shwn intact Cmplete/Ttal Inic Equatin: shws strng electrlytes as ins Spectatr Ins: unchanged in reactin Net Inic Equatin: Shws substances that change in a chemical reactin Guidelines fr writing Net Inic Equatins: 1. Cmplete and balance mlecular/chem equatin 2. Leave slids, liquids, gases, weak electrlytes as cmpunds; break up strng electrlytes 3. Cancel spectatr ins 4. Simplify cefficients if pssible 5. If all reactants and prducts cancel (all spectatr ins) NR Oxidatin-Reductin (Redx) Reactins Be able t determine xidatin numbers fr all the atms/elements in a chemical equatin. Use xidatin numbers t determine which reactant was xidized (reducing agent) and which reactant was reduced (xidizing agent) Determine the # f electrns gained r lst. Mlarity, Slutin Stichimetry, Mass Percent Cncentratin, and Vlumetric Analysis Use mlarity and vlume t slve fr mles Use chemical equatin given t determine mlet-mle ratis needed t slve prblems Slve a variety f prblems cmbining mlarity, mass percent cncentratin, and tpics cvered frm previus chapters. Acid-Base Titratins Knw the definitins fr standard slutin, acidbase indicatrs, titratin, endpint Slve prblems using titratin data. Carry ut errr analysis (hw different kinds f experimental errr will impact experimental results) CHEM 161 Final Exam Study Guide page 3 f 9

4 Chapter 5: Thermchemistry energy: capacity t d wrk r t prduce heat heat: energy is transferred frm a htter substance t a cler substance kinetic energy (KE): KE= ½mv 2 energy assciated with an bject s mtin ptential energy: energy assciated with an bject s psitin r its chemical bnds jule (J): 1 J = 1 kg m2 s 2 and 1 kj=1000 J calrie (cal): 1 cal J (This is exact!) Distinguish between system and surrundings Knw the regins and features f a Heating/ Cling Curve Under cnstant pressure (like atmspheric pressure), q reactin = ΔH fr endthermic reactins, ΔH is + fr exthermic reactins, ΔH is Thermchemical Equatins indicate the enthalpy changes as well as reactants and prducts Be able t slve stichimetry prblems invlving enthalpy changes using a thermchemical equatin. heat (q): recgnize the meaning f signs fr heat q is + fr heat flw int system q is fr heat flw ut f system heat f reactin (q reactin ): endthermic reactin: q reactin is + energy f reactants < energy f prducts, surrundings feel cler after reactin exthermic reactin: q reactin is energy f reactants > energy f prducts, surrundings feel htter after reactin Classify different chemical r physical changes as exthermic r endthermic. 1 st Law f Thermdynamics: The energy f the universe is cnstant. Law f Cnservatin f Energy: energy is neither created nr destryed in a chemical reactin, s the ttal E f reactants equals ttal E f the prducts. Use fllwing equatins t slve prblems: heat = (c s =specific heat)(mass)( ΔT) heat = (c p =mlar heat capacity)(n)( ΔT) The specific heat f water (4.184 J/g C r 1.00 cal/g C) will be prvided. Calrimetry Prblems Use the heat absrbed/lst by water/slutin t determine heat lst by a metal r assciated with reactin t determine ΔH r specific heat f metal (e.g. Calrimetry experiment) Guidelines fr Thermchemical Equatins 1. The magnitude f ΔH is prprtinal t the amunt f reactants and prducts in the equatin. 2. ΔH is the ppsite sign fr the reverse reactin. 3. If the cefficients in an equatin are multiplied by a factr n, ΔH must able be multiplied by n. Hess Law: The value f ΔH fr a reactin is the same whether it ccurs in ne step r several steps: ΔH = ΔH 1 + ΔH 2 + ΔH 3 + Standard Enthalpy f Reactin ( ΔH rxn): Enthalpy change accmpanying a chemical reactin at standard state cnditins Standard Enthalpy f Frmatin ( ΔH f ): Enthalpy change fr the frmatin f 1 mle f a cmpund frm its elements in their standard states. Slve prblems using ΔH rxn and ΔH f : Be able t calculate ΔH rxn given ΔH f fr all the reactants and prducts Be able t calculate ΔH f fr ne reactant r prduct given ΔH rxn and ΔH f fr the ther reactants and prducts. CHEM 161 Final Exam Study Guide page 4 f 9

5 Chapter 6: Gases Knw the physical prperties f gases Gas pressure and Atmspheric pressure Standard atmspheric pressure: 760 trr at 0 C Cnvert between units f pressure: 1 atm 760 trr 760 mmhg Knw hw a manmeter is used t measure gas pressure fr pen systems (p. 2 f lecture ntes). Slve fr a variety f prblems invlving gases P1V1 P2 V2 Given 2 sets f cnditins, use = and T1 T2 cancel variables that stay the same t simplify, and temperature must be in Kelvins Use ideal gas law (PV=nRT) t slve fr P, V, n, r L atm T. R= will be given. ml K Recgnize that STP is standard temperature and pressure, defined at 0.00 C and 1.00 atm. Use the ideal gas law and unit analysis t slve fr density, mlar mass, and ther prperties. Slve stichimetry prblems using 22.4L/ml at STP and n= PV fr ther cnditins. RT Daltn s Law f Partial Pressure: Use Daltn s Law (P ttal = P 1 + P 2 + P 3 + ) t slve fr ttal pressure r the partial pressure f ne gas in a mixture Mle fractin: X A = # f mles f A ttal # f mles in mixture Partial pressure (P A ): P A = X A P ttal Slve fr mle fractin, ttal pressure, r partial pressure given ther variables Kinetic Thery f an Ideal Gas Knw the kinetic thery f gases regarding particle vlume, particle mtin, attractin, cllisins, and the average kinetic energy f each particle being prprtinal t the temperature. Mlecular Speeds Knw that u rms is inversely related t the square rt f the mlar mass f a gas The higher the mlar mass f a gas the slwer it mves Diffusin: gradual mixing f mlecules gas mlecules by virtue f their kinetic mtin Effusin: prcess f a gas under pressure escaping frm a cntainer via small pening Identify the rder that several gases escape ut f a cntainer using mlar masses. Real (Nn-ideal) Gases Recgnize under what cnditins (lw pressure, high temperature, large vlume) gases tend t behave ideally and why. Chapter 7: Atmic Thery wavelength (λ): distance between successive peaks; generally given in m, cm, r nm Knw 1 m = 10 9 nm Use equatin: c = λν speed f light, c: m/s (will be given) frequency (ν): number f crests passing by a given pint in 1 s; given in 1 =hertz (Hz) s wavelength (λ): distance between successive peaks; generally given in m, cm, r nm Knw 1 m = 10 9 nm Use equatin: c = λν speed f light, c: m/s (will be given) frequency (ν): number f crests passing by a given pint in 1 s; given in 1 =hertz (Hz) s Relate energy, frequency, and wavelength: E=hν = hc λ Dual Nature f the Electrn Electrn can behave like a wave r a particle CHEM 161 Final Exam Study Guide page 5 f 9

6 Chapter 7 (Cntinued) Planck and Quantum Thery prpsed energy is absrbed and emitted as bundles = quanta single bundle f energy = quantum Einstein and the Phtelectric Effect Be able t describe the Phtelectric Effect Knw this prvided experimental evidence fr light existing as particles = phtns Bhr Thery f the Atm Electrns mve in quantized rbits called energy levels arund nucleus grund state: electrn in lwest energy level excited state: electrn in higher energy level When atm absrbs energy, electrn jumps frm lwer energy t higher energy level. When electrn drps frm a higher energy t a lwer energy level, it releases energy, in sme cases as light atmic emissin spectra Knw limitatins f the Bhr Mdel Recgnize energy levels further frm the nucleus are clser tgether Calculate the change in energy ΔE fr an electrn mving frm ne energy level (n initial ) t anther energy level (n final ): 1 1 ΔE = J 2 2 nfinal ninitial Be able t write electrn cnfiguratins fr any neutral atm r in Be able t write using full ntatin and cre ntatin (Nble Gas abbreviatin) grund state: electrns fill lwest energy rbitals first excited state: electrns in higher energy rbitals befre lwer levels filled Recgnize extra stability gained with filled and half-filled d rbitals (Cr, M, Cu, Ag) Accunt fr electrns gained r lst fr ins Knw Representative Elements usually frm ins that are iselectrnic with a Nble Gas Nte that transitin metals, Sn, Pb lse their s electrns befre their d electrns. Be able t draw atmic rbital diagrams Knw Pauli Exclusin Principle Knw Hund s Rule Shw that each sublevel is slightly higher in energy than the previus sublevel Knw definitins and peridic trends fr atmic radius, inizatin energy Knw Inic Radius trend: r catin < r neutral atm < r anin Quantum Numbers (n, l, m l, and m s ) Knw the restrictins n each and the rbital described by a set f quantum numbers. Chapter 8: Bnding valence electrns: utermst electrns the grup number fr each element is equal t the number f valence electrns it has electrnegativity (EN): ability f an atm in a bnd t draw electrns t itself Knw F is mst electrnegative, further away frm F, less electrnegative an atm. inic bnd: electrstatic attractin between catins and anins, hlding the ins tgether in an inic cmpund cvalent bnd: sharing f electrns between tw nnmetal atms plar cvalent: unequal sharing f electrns by 2 atms with different EN values nnplar cvalent: equal sharing f electrns by tw atms with equal EN bnd length: distance between nuclei f 2 bnded atms; shrter the bnd strnger the bnd. single bnds are the lngest and weakest duble bnds are shrter and strnger triple bnds are the shrtest and strngest CHEM 161 Final Exam Study Guide page 6 f 9

7 Chapter 8: Bnding (Cntinued) ctet rule: atms bnd such that each has 8 electrns, except H nly needs 2 electrns. Draw Lewis Structure (Electrn Dt Frmulas) fr Mlecules & Plyatmic Ins Exceptins t the Octet Rule Incmplete ctet Be can have 4 e s, B can have 6 e s, and N can have an 7 e s Elements in the third perid and lwer can have an expanded ctet (>8 electrns). Lewis structures fr ternary xyacids Oxygens arund the central atm, and ne hydrgen each bnded t an xygen Frmal charges: hypthetical charge an atm wuld have if bnding electrns are shared equally and lne pairs belng slely t a single atms = ttal # f valence electrns in free atm ttal # f nnbnding electrns ( ) ttal # bnds f Use frmal charges t determine the mst plausible structure. Minimize frmal charges fr mlecules where the central atm can have an expanded ctet resnance structures: tw r mre structures representing a single mlecule that cannt be described fully with nly ne Lewis structure Recgnize which mlecules require resnance structures by drawing electrn dt frmulas fr given examples. Chapter 9 Valence-Shell Electrn Pair Repulsin (VSEPR) Mdel repulsins between electrns give rise t the shapes r mlecular gemetries f mlecules Be able t predict the shape f a mlecule using its Lewis electrn dt frmula. If there are nly tw atms in the mlecule, then it s linear. Fr mlecules with 3 r mre atms, determine the general frmula and match that with the crrespnding shape. A=central atm, B=uter atm(s), E=lne pair(s) n central atm AB 2 linear, 180 bnd angle AB 3 trignal planar, 120 bnd angle AB 4 tetrahedral, bnd angle AB 5 trignal bipyramidal, 90 & 120 angles AB 6 ctahedral, 90 bnd angle Variatin n trignal planar shape AB 2 E bent, <120 bnd angle Variatins n tetrahedral shape AB 3 E trignal pyramidal, <109.5 bnd angle AB 2 E 2 bent, <109.5 bnd angle Variatins n trignal bipyramidal shape AB 4 E see-saw, <90 & <120 bnd angles AB 3 E 2 T-shaped, <90 bnd angles AB 2 E 3 linear, 180 bnd angle Variatins n ctahedral shape AB 5 E square pyramidal, <90 bnd angles AB 4 E 2 square planar, 90 bnd angles Draw Lewis structures fr mlecules with multiple central atms. Determine shape and bnd angle arund each central atm Recgnize that in xyacids (e.g. HNO 3, H 2 SO 4 ) the H atms are bnded t the O atms. bnd energy: energy required t break a bnd always psitive Use bnd energies given t calculate ΔH Plarity Use the shape and electrnegativity differences t draw diples and determine if the mlecule is plar r nnplar CHEM 161 Final Exam Study Guide page 7 f 9

8 Chapter 9 Valence Bnd Thery Recgnize that tw atms frm a bnd because they share electrns t becme mre stable The bnd length (distance between nuclei) is achieved by balancing the electrn-nuclei attractins and electrn-electrn and nucleusnucleus repulsins Steric Number (SN) # f uter atms = + bnded t central atm # f lne pairs n central atm Hybrid Atmic Orbitals Identify fr the central atm(s) in a mlecule: AB 2, linear (180 ) SN=2 sp AB 3, trignal planar (120 ) r AB 2 E, bent (<120 ) SN=3 sp 2 AB 4 (109.5 ), AB 3 E, AB 2 E 2 (<109.5 ) SN=4 sp 3 AB 5 (90 & 120 ), AB 4 E (<90 & <120 ), AB 3 E 2 (<90 ), AB 2 E 3 (180 ) SN=5 sp 3 d AB 6 r AB 4 E 2 (90 ), AB 5 E (<90 ) SN=6 sp 3 d 2 sigma bnd (σ): bnd frmed frm direct verlap f tw rbitals frmed by single bnds and first bnd fr duble and triple bnds pi bnd (π): bnd frmed frm sideways r indirect verlap f tw rbitals n a separate plane frm the sigma-bnded atms frmed by the secnd and third bnds in duble and triple bnds. Identify bnds as sigma (σ) and pi (π) bnds using the Lewis structure f a mlecule r plyatmic in. Mlecular Orbital Mdel Electrns in mlecules ccupy mlecular bitals electrns delcalized ver entire mlecule, nt just bund between 2 atms Explains resnance, bnd strength, and paramagnetism f mlecules mre effectively than Lcalized Electrn Mdel Chapter 10 Describe slids, liquids, and gases in terms f kinetic energy f their particles and mlecular mtin. Inic Cmpunds Culmb s Law Relative strength f an inic bnd is given by the fllwing: Charges f ins: Higher the charges strnger the bnd Distance between tw ins: Shrter distance strnger the bnd lattice energy: energy released when gaseus ins cme tgether t frm an inic cmpund Recgnize hw melting pint and lattice energy are related t the strength f inic bnds In-Diple Frces: attractin between an in and plar mlecule (e.g. Na+ and H 2 O) Intermlecular Frces (IMF s): attractin between 2 different mlecules in a liquid r slid Identify IMF s experienced by mlecules. Als called van der Waals frces Lndn/Dispersin (Induced-Diple) frces: attractin between mlecules with instantaneus diple resulting frm electrns shifting nly type f IMF s between nnplar mlecules experienced by all mlecules becmes strnger with mre electrns the mre electrns in the mlecule (higher mlar mass) strnger the Lndn frces Diple-diple frces: attractin between plar mlecules withut H O, H N, r H F bnd Strnger than Lndn frces because plar mlecules have permanent diples CHEM 161 Final Exam Study Guide page 8 f 9

9 Chapter 10 (Cntinued) Hydrgen Bnds: attractin between plar mlecules cntaining H O, H N, r H F bnd Strngest type f intermlecular frce Inic and cvalent bnds are strnger than any intermlecular frce, even hydrgen bnds. Intermlecular Frces (IMFs) and Physical Prperties Knw IMF s influence biling pint, vapr pressure. Use IMFs t rank substances in terms f increasing biling r melting pints. nrmal melting pint (m.p.) r biling pint (b.p.) always at 1 atm Intermlecular Frces vs. Inic/Cvalent Bnds Distinguish between IMF s between different mlecules and the chemical bnds (inic, plar cvalent, r nnplar cvalent) hlding atms r ins tgether in a cmpund Identify type f bnd made r brken fr a chemical reactin r a change in physical state. Structure and Prperties f Water Because f hydrgen bnds, density f ice is lwer than the density f liquid. water has relatively high m.p. and b.p. Crystalline Slids: w/ regular, gemetric pattern Identify a slid as inic, mlecular, r netwrk cvalent (graphite and diamnd) given its frmula. YOU WILL BE GIVEN ALL RELEVANT CONSTANTS AND A PERIODIC TABLE WITH ELEMENT SYMBOLS, ATOMIC NUMBERS, AND ATOMIC MASSES. THE EXAM IS MULTIPLE-CHOICE SCANTRON FORMAT, SO BRING A BASIC SCANTRON FORM, A #2 PENCIL, AND A BASIC SCIENTIFIC CALCULATOR. CHEM 161 Final Exam Study Guide page 9 f 9