Class Note for CHEM 241 at UMass(5)
Class Note for CHEM 241 at UMass(5)
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Date Created: 02/06/15
rr 1 92 L Chapter 9 Hydrogen Diborane mm is the simplest member ot u large class of eumpounds the elmran dt clcnl boron hydride Like all bumquot ll rides it has a positive standard free energy of formatian and so cannot lie prepared directly mm boron and hydrogen The bridge 8 bonds are longer and weaker than the tennirtal EH bonds l 32 S 1 t9 At a e9ees 0 e a Reactions it hydrogen compounds 3 Cats Hzlsl gt Calljsl This is the reaction ul an uL lIVc intctal itli hydrogen which S the way that saline metal hydrides are prepared h NHiLEl mug a ll rBFig This is the reunion urn LENS bust and 3 Laws mi The prnducl IS a Louis unHusc complex t LiOHtsl v Hug gt NR Althiiugh tlihydrogeit can behave as an mulanv ti 3 lll1 Li to form LiH or asa rcduciani c g with 0 in form H0 l does not behave as a Breasted or Lexiis acid or base ll does not react itli strung iiscs llkL LiOH ur With strong ands procedure for making EttnIcSn A possible procedure is ts rollows39 EIEliSnll ZNa 4 ZVa EliSn r H i39EtSn Clli r a EtJMeSn v NaBr Where doc llydrugctt quotI in the periodlc than a Hydrogen in group I Hydrogen has om valence electron like the group I metals and is stable as H39 especially in aqueous media The other gruup l metals haw one talenei clcclrnn and arr quite stable as M cations lll solution and In the solid mu as simple trim salts In most purler Clla S hydrogen is generally put Hll l this group gncn the above mt39ormniion llnwcvei plumally hydrogen does not lit in this group l IS a diatomic while the group I metals are Just that metals Your text tines mention hat hydrogen may exit IS a solid under extreme pressures h Hydrngcu in group I7 Hydrogen can ll its ls orbital and make u hydride H Hydrides an liocleclronic m He a noble gas con gumtion thus are relatively stable Group l and group 2 melals as null as transition metals stabilize liydndes The halogens farm stable X anions obtaining a noble gas Inl lgurllllom bolh iii snlutiun and In the solid state as Simple tunic salts Smite periodic charts put hydroga bath in imiup l and in group I7 for the masons stated above The halogens arc diatuntic gases tug like titurogch 5n physically hydrogen ts well n gnup i7 but chemically ll ts well in bath group 1 and group I7 m Hydrngen ln group m rim is no reason chemical or physical rnr hydrogen in be pldccd In this group Luw reactivity til hydrogen Hydrogen exists as a diatomic molecule H1 It has a high bond enthalpy set Table 2 5 thus it Likes 3 lot of energy to break the hand It also only has two electrons shared between two protons VlllCl l is energetically very stable leading to its chemical stability Assign oxidation numbers m elements a HS When hydrogen IS lESS eleuronegatne than the other element in a binary companiid H is 2 20 S is 258 set Table l 8 its oxidation number is chosen to be H Therefore thi oxidation number ufsttll ur in hydrogen sul de sulfuric IS 71 74 94 05 91 Chapter 9 I39lydmgen 75 b KH ln lhls case hydmgcn lZJO us more clcclmucgaln c lluln potasslum 081 so us uxlmnon number Is chuscn to he l39hcrcl mc lhe oxnduhun numbcr of potassium In pumslum hydndc S 4 I c IRcHulz39 The clcclronc mvlly nl39 rhunlum is no given In TIME 839 Howcvcn 39incc 1 IS a mL lul I Is reasonable 10 conclude that u IS lcss clcclmnegnuvc lhun hydrogen l hcruforc If hydr cu ls counted 15 Khan the rhenlum mm Ill xhc chlhquot um has an axld lmn nunth 0P7 d 150 The slrucunc uf sulfuric Bull is shown below SIHCC the hydrogen Ilum are bound l0 vcry clcclronegalnc oxygen ulum their uxldulmn uumllcr l H Furlhcrmorc sulcc oxyan lS always asslgnLu un uxlduuan number m2 u pl for 02 um peroxides sulfur has in uxldunun number of m ll l ll v d n P Om5 H 11 OH 0 11 Hso4 H2P0Oll 2 quot1mmquot 2 The snucmrc ofquothypuphuspllurous ucvd also culled phosplmuc acid l5 shown almvc 39l39hcrc um um lypcs of hydrogen alums The one lhal IS bonded xo un mygcn alum has an audauon numbLr of I IV The hm lhul up hundud n he plmsphurus uom preset a problem sum phosphorus 1 I ll and hydrogen 2 10 haw nearly equal clcclmncguuvmus ll lhcsc two hydrogen mums an assxgned an undulan number or lm oxygen as tum I sslgncd uh nxidulian number ufrl lhcn the phnsphnrus alum m llzPDOll has an oKldqun number of Preparation nf llydrugen gns As discussed n Scclion 93 mommy and n urlimn Qflliu39dlwgylt lhc Ihru mduslnul mclhuds or nrcpurlrlg H are ll steam reforming n he rahth rcuclmn and Ill th ylnl l reacnon ulsu called the wmcrvgus shill ruuclmn The balanced cqunlmus are m Cl39l lg 20 aCOlEJ 311ng 000 C m CG 4 0 a COlg Hug Howe unl COIgl H10 a 3902ng llzlgl Thus rmclmns m not very nnnvenienl for he pmpuraliun of small quantum nl39hydmgcn m Ihc labornmry Instead ivl Ircalmrm or an and wuh an active metal such as Zinc or v lmnlmcnl of mm hydndc wuh zucr would be suxublc The balanced cquzmnns Mr M 1m 2HCIlq Znquotuq 1Cl mm Mg m NuH5 0 aNa laq Oll laql Hug Prnptnics nl hydridrs uf hr ltnlenlsi u Pnsitiun in he perlodic table See Fxguru 93 h Trend in A1quot Sm Table 96 c DIHCrcnl nlnlccular hydridus Molecular llynlrllles are fouuxl In groups l3 lll lhrough l7VlI Thusc in group I3Lll an cluelrundc clcnl lhusu in group HIV are clcclmnprccise and lhose In gruup SN lhrough l7Vll arc clcclmn nch What are u physical propcrxics or water Wlllmlll hydrogen bonding RcurJ Scamquot 94 h Iiwlmgz39n mulling Il39 wumr dld nol have hydrogen bonds u mos hkcly would hC a gas a room CmpL mLurC hkc us hcancr homulugucs 5 lec and 1 1ch sec Figure 9 Also mnsl pun compounds arc denser as a suhd 76 97 98 90 9I0 Pan 2 The Elcmems and llleir umpmlnds Because of IIydrugcn bulldlng water 5 actually less drnsc and has the slruclurc shown In If lhcrc IVch quot0 hydro n bonds It would be cxpLclcd llml Icc would be lluln as u liquid gur 115 This 5 why lu ouls denser than LIle mm molecule has lhc stronger hydrogen bunny IlydmgLn bonds conslsl Ola Iljvdmgcn alum bonded In In alum more clcclmncgalm lllun usclf LC F and 0 See Table l 8 This render pulunly bclwnen lhu 1 H buml E z a pblnck lelmclull and ullnws Llunauun u a lone pm from anolhcr nIolcculc m lbrm Illa ludroucn band Smuc S ls cluclmncgulivc lllun 0 ll plmml pnslInc charge full by Illc H lll 07H ls stronger lhan Illul In S rH lhuruorc 33gt O has 1 Walker hydrogen hand man 07H 8 Name and clanin um following u mug 39rms cmnpound ls mlrncd hanum hydndu ll l5 SalIIIc mm b Silhi Thla mulpuund Is nunch Sllunc ll Is an cleclmnvpmclsc molecular llydndc lc NIL ThlS l nmlllur compound IS known by ll common numc ammonlzL rulllcr lhan by he syslcmllllc nJmL S unnc m mlmnc Ammnmn ls an clcclronalch molccular Ilydndl ll Aslh Hus cnmpnund Is generally known by us cnmmon name lusmu mlhcr Illan hy us syslcmunu mum mm ll 5 alsn an clcclronnch molecular llydndc u Pdlhm U I Tllw compnund is known by Its summon numc hydrogcn Iodldc ralllcr IhaII by Its syslenlllllc name nodal ll IS an electron er mulcculur hydrldl nlis compound 5 named pulluLLlum llydndc ll 5 a nIL39IzlllIc hydrldc Chemical churnrlerlstirs ol39 hydridm ll Ilydridic cllnral39ler39 ll rcucls ulh pmlun sources such as H10 lo farm H Bunum llydndc lsIgum 1culIIplL 5mm Imus l ZHIOlllalH g l amount Nclrcuclmn 1 zll39 2 b Brnmled acidily Includng pyrldlne Hydrogen lodlde ls l gnod cxamplc slncc ll lransl cr lls prawn lo a vancly of bases m Variable composilion39 The L39oIIIpquId Pdl In I IS a we mmplc d Louis hasicityi Ammuxllu ls l gond cxunIplc smcc ll fm ms mudbase complexes ml39n u vunely or I cwls uclds mcludlllg HMc NHllg 39 BMellgl IthBMmlgl Pllasu u hydrldns ul39 IE clcnlcnls39 Ol39lllc compounds Ilslcd In Exercise 16 Bull and PdHW ulc sululs Ilunv IS a Ilquld md Sin Nllx ASH and HI arc gases sce Flgure 1 l Only Pde IS llkcly In lac a gmld L lcclnc l conductor 1 l2 lmplur 9 Hydrogen 77 TlnV slru urus n quot15139 lull and 0 The Luux lruclnrcs nl lhusc liucc spent 1 7 H H H Aucunlmg m lhu vs I R modd sec mum 2 3 111 u should u hunt and in u taclonm m liw r puml gum nu lthould In rIj39un mmmnm vhkc mm m s o u hulungx m His 1 Mm gruup my phosphurus Mom or 14111 shunld mu mu pyrulmdnl structure Irma molecule uu39npls me an confommllun lice mu cuman dlngram bciou r then u belongs m he 3 pollquot gnup uh y mus hlsccts m P r1 bum A leuan mm uuum r ram The v P m 1 I hand mmmee m 2 2 and z 4 espucinch md u P P lllmlvduugluadrczlll41mmU4 1cf PII mwlucmlm LP ll Immng ma 3 um7 m A Mm prujc nm 0139 Inc 5km m murhe cunlbrlnulmn nl39 I h 391 In Uulv clcmcnl u1mucu Im Hus l 2 ms 17 b xhc I P lmnd l39hcl39ulorc H Inn r39 qmczuru pns cs Inmclry l39lw rcurtiun mm in give he luighm prupnrliull M um Rmcuau m and m hm mum he pmducnnn 0139 hum H and I 21mm M II nul39lllrc Ufa mum 39Ilu ICCmIIhIVLIUDH of u sc alums HH gnu I cumucul dMnhunnn m H Why HD 50 Am D 25 Hnumcr rmcnnn lbw znnrlus Amch nf prawn Um I mm H39 u c D39 r and a salute nfhydndu mm Uul vs mmquot 39H 39 IEU Nll5 g NAODM ctrcm lmn D II a HD I lms rcdcnnn a u 1H praducc lulr39w HD and no H or D MAM likely lu uudurgu rmlirill rem liom N39lhc compounds 0 NH lCH QIIL and CHmeIH 1h nu compound 15 Ilw mm hkcl m umlcrgv ludu nl mutual mlh nlkyl Iluhdcs Tins IS humus th Surll bnnd m L39H IISnH Is lcss pulur ulnl vcukrr IILJII cllllcr LII rH ur S H l undi Tlu I39ommlluu of mdcls vnurlu s me nonmum clmmgc mm band bcmccn hc ccnu39u clunlunl and hydrogen and J m nunpulur mud nnlergncs homnhsls mo rcadll 78 914 916 917 9AM 9J9 Purl 2 The Elements and Their Compounds Arrange 110 quot5 and quotSL In urder39 a Increasing xcidlty39 s dtscussed tn Scctton 43 Pvtunlu trvmlx In aqua mhl snwthr uctdtttus of EHI tncrcztsc down a group tn the 1 hlock mostly bccuusc the decrease m E41 bond cnthulpy luwcrs tltc prnton amnny ul39E11 1E 15 a generic pblonk clcmcnll 39l39hcrcforc the order of Increasmg acidity ts 0 lt H23 lt HSe h lncreaslng hulclly toward a hard acid In gtnerttl 50ft character tncreascs down u group so the hardest hast ofthesc thrcc cuntpnunds is 1120 The urdcr of tncreustng b sk ll39 toward a lturd uctd ts Ills lt 115 lt llgo The synthesis orbinnry hydrogen cnnlpttumls39 The three ntutn methods orsmhes of btnary hydrogen compounds trclt dll L Cl cotttbtlttlllun ul39tlw clcmcnts u protonuuun nfa Brunstcd base and In mctathcss ustttg a compound such as 11 EH or LIAIHJ The rst method ls hmch to those btnury hydrogcn compounds that are L VDCKgIE An exumplc Is39 I The secnnd mctltud can be uscd fur the ttrcpurulton of E11 compounds when a sttutcc quot139 the Equot linkquot ts uxatlublc An example 1539 2mm r Hglgla mum ii Cums l 113504114 21mg r 050m Almost nu of mu hydrngcn llunrtdt mm 5 prepared indusmally is made this my The thud ntmhud can he used to mnven the chlat39ldcs nfmany clcmcnts i m lhc currespnndtrtg hydndus as n the fullnwmg example P lll lLtHls gt l Hllg JLIC lts C nntpare BH AIIL39 and 63H 393 Since Al has the lowest ulcclrnrttgattvtty of the thrcc clcmcms B 204 Al ll 6 and 11081 sec Table LEl the A1711 bonds of A111 in more hydndtc than the Bill bonds of 811439 or tltr Gu l39l bonds ol GnH T39hcrcl nre sinc AlH ts murc llyLlndCJlkC tt IS the strongest rL duClng agent The rcuctmn area I39 wlth uqheous llCl Is a allows 64th 39luq 4HCltaql v each tag A 4Hgl Compare period 2 and pcn39od 3 hydrogen cunnmunds One Important dirrcrcncc between pcl39tud 2 and pertod 1 hydrogen compounds IS tltutr rulnttve slubtltttcs The pctrod 2 compounds except for 511 arc all cxocrgtc see Table 96 Then period 3 homologuus either are much less uhucrgtc or are undncrgtc 1 HF and CI for whtch AL J732 and 7933 k ntol 39 and NH and FH for whtch AGquot 4165 nndl4 ILI mor39t Anutlter importth rhemtwl antenna is that period 2 compounds lend to bc Vcakcr Bronsted actds and stronger Brunstcd buses than tltctr pcrmd l Itontolugucs leurunc 112111 is a gus Wl39tlll AlHJ ts a sultd Methane TIL ts men to oxygen and water Vl lllE silunc 1114 reacts tlgomusly vuth both Thc band angles tn parted 2 hydrogen cumpourtds rcllecl a greater degree of xp hyhndtyatton than the ltumnlugous parted 3 cnmpnunds cuntparc tln 11 Gl1 ttnd lliNiH bond angles 0139 water and ammonia whtch are 104 5quot and l06b respectively tth thc 139l S II and l l P I39 hund angles nfhydrogcn sul de and phosphune which ztrc 92quot and 918quot respectively Several penod 2 compounds xltlbil strung hydrogen bondtng ntlmcly HF 1110 and NH whtlc their parted 1 hontolngucs du not see Figure 94 A5 a consequence of hydrogen bonding the hotltng patttts oI HF 110 and NH are all ltlghcr lltlln tltctr rcspccttvc parted 3 homologue 5crihlt the compound formed between water and Kr This cnmpaund IS called it cluthrutc hydratc tscc Scctton 940 It cunststs of cages of water Ittolucules all hydrogcn bonded tugcthcr each surroundmg u smglc krypton atom cf the structure at the clathme ltydrute of molecular chlmnc shown In gure 88 Strong dtpult dtpolc forces hold the cages tngclhcr vhtlc vcakcr van dcr Wasals forms hald the krypton atoms tn tltc centers nt thctr rcspcclwt cages Potential energy surfaces fur Ityurngen bonds See Figure 97 liter arc hm Important dtfr crcnccs between the potential energy Surfaces for thc hydrugcn bond between H30 uml Cl ton and for the ltydragcn bond tn htilttortde tun HF339 The rst dthcrcttce is that the surface fur thz 110 T system has a dtvuhll
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