“or — } " yucleons ” ing a 8 “1: a 1. ey undo = 41x03! cy pret en > 1.6425 16771 hp mass of neutton - 1645 x16 ig. ck elect ow wp Mads of Be eee Chl "th fink proton ond weussion- “during a churvical aN > yuu A of etucktens ¥ v but yun?» Of prere @ ee surnames pind toon vas (yoni) oT 1° 7 as : 2 a ~ ues, Wing we wue cu an atom? z 4 pdprn = Noe ad of msi v | ross ~ 4 beer youl med) unipted nas (4) * ea x(mans Seon) Cit) a) eb (hens * aon nucleons) rir: (nx ah 12 ° auc L(g) masa af aac Nucleon 2 4u> Tue Ib pe ea 4 azomic MOSS dhe mays F Oe wong 4 MM ese f vi le ees 2 NESE AIGOAIO 4 i There man = 18 fama “Nansen 38 SiN x moet ee te fp HR mae af AM beQuy, + a nel cee Hmbih ag malocuees ® suy NH © OF Umetecutes M43 = Ea “S429 matoeules in L 8 adevu 5D 8b. to, Wess OF | nwotecwle> 44 su & 88 29 wootecule Tie hs utes Ralotive Asomic Ree WAH t RAM = Atomic moss _ noe x MOU Here mat to Tee RAM= no. OE nucleory © SiMiLay males We howe PUSAN emo Tat (eM.M) & Porunula Madd Te ta med dm case 94 Sore vetmpouund cy - Fewnuter mors op nad 33435:'S= $85 Rae ov win Af He Mea? a) Cg Hind b) Co Omura A) cer —# 35-5 a mens een , A mole of 0. Susapsio’ ot anak 0M oun cnt peiaa bs lax 66 nior4)4 Pee 4 kom Un ae 1 . 44 b> 4342445 wiurLy N 3 F Tmale= 6023 X10” particle} pkonuic Maus (GAM) * agree D hr Ams ne-of nucleens 4 4 Fg. Molar Mod of @> N= IY Np = Ma uy $2 324 a Oho Sates ay je due nnns of 4 mole @ oe il hiae RABIOT "molar rnass (dy Co, = Ny Ui) Ne = 884 (Hi). Sey > 644 cue . (arteulate, Mo- Of atoms wn? a) Sig HE SDA Ny > 43Nq neem 4 by 364 0 = aN Np toma 6) 92KS = 322 Sater 32. debu P= 6% > ran ‘toe e649 02 64%Na 2 YN, axes 6 M44 He AWA = iN, aKea + So 0 UO 8. Ve =. ques, 486 lon EEE KCHCKHHCOH SH GSHSS uy 6 mete C, HO wniains te mete of-C, s-ll (i. ausey, Equivalent mass of meta rayelrude bs 13. cadeutade 04° mau Gob Eq. mass oF metal - iby mi aa oO aaA mete 0 mote OF mete 6 92 oro. of Cason F1Nn ‘no. of H atoms BNA ne 0 atoms Beno, of Hy rmelecuclas bx Ise 4 Ce Hy % 24 CHy orneuns 2 matachy 2Na_ re 6 CHy (ONA no, of atom 4 Epa Mans (E)* Method. Heuiwatard maw of 1 subystomen 1a daginad ay me of povcls bip Ligh ta stows Commbunes Wier ar alaplace, Spork boy weight of gels (3-2 at STP), 8 ( part a by vantage OF omlortine 2 L tly at STP) ta onkde, 4, raasey- nes Sen P messy meter 2122 f Fiabe eniges Pt +89 = St pa sramdanal THmp. ancl Pres Lt He total mats betoog eee Gog. metal aq omyye He me sqomyyin— OBx8= pg meet 3.64. MAKOE nese = 12-9 due 05 tae choral de 44 Uo-5 caeubecte oy massef matt Etude Se tg. ras Of meter cuboride= Et 355 Dass Yo5, D> Esso 1a Of muta onide = E+ 85. > f0ts = 114, dnd Method, Veyadvalont nas con aie be caLeubaed in kos py \motar Mass’ ee Meter Mass fee. Dd n-factor (m)> wen- vam TelMur beCronies Hoy y He 4 Hog, 4 Ha po, a Ha Poy 2 Ha Po, ‘ H3 Bog a ° 1 F ay " h | Fou) [Hates (2) Pon EEE Sat: an facto do Caa Aha a4 tee tVA AY cree MN. oS a pace KyS0y 2 AL Wy a feSoyqsHa)soy 6 Ak, (S04), “| vp Pox Bases bse, example * oe 6h KOH NAOH 4 Ca(oH)2 2 ALLOH)3 g . jenetipn ea ree gia Aa | ee ow denatd He + wen is not ln Hon ne porckok do #0 the Mar, Ne OF HA gi OW tend donoutta acid A bose SUApactt. Oy, oUt Y Hut dndined ce HF | dol. HU, sevinked one Lew ‘banes 4a diginet oes on ieny os cm 10 °F abecule aul yoleasca by 3 Baw cy Acidity 9p Amat bo metor mass i alow), +2. fon WE cottaaMee So eS npacton = 4 Brana Mic M (toe HP, eae — Naso, + HO G4. yay = MoM 4 fll) Hy Poy + NAOH e223 104 t2H0 2 Ww) CA(OH), + RU— [aloH)ee +H,.9 -joaten =1 anaes M4 __ aaatereceeree reBue. tnJeutoce oguivatint masa op snydsvoced arabic avid Te Avy. goatic acid => FOC% DeaH204 coon Te Ayplraded. orealie.. ¢, iy 04-2820 Tr *Mabs of hydrated. r ’ = rz o ocatte cle ) 2012+ 2+ Y(le) + (18) I 2) Ut2+64 +36 he 7- Of "8 are be % Wen » ‘/s of 'B = 100-% . AY (0d +0) 00 0-8 abiiie 2 joo moss eT > Qo ea > 10% $\oO- MN 2 1p-8 2 n-factor = 2 i DEM-Mnss= Malod MAM _ Job = 63 D —m tiloo > 1080 nfacor =D t —me — 20 *ASHZO da a veup week HE 20/0 elect thats wig HE tons % og'B = hy ie ara raglighblt. | 7, of "9-807. 6. dallas) - oom ca = You = 40 x1007 4% 100 400 f 44> Leotopes G2 12 = 12 xIo0= 127+ = Lastepe, Joo 4 9 = ABm 248x100 = 487 cunrerine nist im 2 lastepie Too : germ 350L ond. OL dm He outs «5 val. of Gn eadoutatt wate 3:4, oaleulate is vorapaund. 4) “poet fi frome Mads. See recon NOUS OF firs. Lot tre corruman Mage bert Corp niumiralua raps wn, sy. SS ne Rivect dre J sat Lae sah ‘on oanionry stom Un. anal > 4n= 100% > 17270 whey if = 2m Jo of SCL = Bu= HS7. tL of th = 25") Wy, 54S )4 (3325.1) 7605+ prone > a05° loo 00 vee loo sy ye 82X08. gow Dp 3550) Boe. nat E Sa eon Mim. apraestok compound peorwould bom.+ ° EMpericad rast a {ous Kea posumilas 12 _fntiond a empaniear as oad Founula? Eabal 3t Hepreser aunpi oa ee ; reas rmulas Caan “a Oe * Maerua, Dhe vtact Empurcca rive Empudicol | Fosunviite CH,0 6 NH,O0 NH, NH CONH 2 + Fxname, | tate Oy 2 CHy Uy 4 Come | myo, HO 2 - pororide | pou density = _notahy NAB ier drool exorms ony Bue, Wher io ne vanplear ovmuteu A db 80 lar Seah 20,.Dp malar mass to 30, cotoulate 16 Pina . % lama: BIB ag a Corben 80 yp 6-66 a Huplogn 100 4 20 x3 nico Porruule = CH3 Euetnical Wa mos3=30 toy, aReysined = Hee a Re mil a P ——— ween Qu. peompound ee t sqouesi341- of Cy 9-04 oF H gust etygws x eee 2 904 Jo0- (S4-54 -1°09) ii c malar Yo ) C44? by no -th yt, OH Cyl g Or Oy Cea cotchoyvit! combi notion, et phonic. Henctton ee ‘ reer kd ce ap § (om 62 “I oat rang ee % ee | er Papssiomental volo , tout, a, Urenaiead I : te Ba xe . yi2 *Hiphegew ome 90ygen tee fl ho, 5 {2} + Ni theque ord onyqur Qx(Woyp ar 322-64 QAWoy — x2 hx7=32 Huo... 98 anal Emes NO? a8 ug 248 380 Moco 38 30 DY 3es Bueds, Pin wonion, Leung, aur ap mubliple® propartion 28 Noe De H,0 Od 1,09 W.n,0and D207 cathe Dae A. KGL omd Kor7 Kot Be 5 chy aaah eames Dou oF Se Proportion’ when 3 @ elements eambined sith Covchy Sor 12 v By enon cxpbusnds shee val 4 Connbines ysitr ne peed tare Ane Hind olpny of aie some 2h wilt odie, Ww vetuch. atively combines ity Lac othr. ine in PO plo K ty a a + ld 192322328 fo: | whanow comnbinn® ae sya vitad yaoelton aver AF Awseys As So iw Sing I visnote ato, guodle at suey | Ques Loe rey end Oe wae dW 5 12% 32 2 vn suas ome PHO" ony to [om 2 ne 1032x2764 TAthl > 12 404 | 3916 | waraen,s oye tod (2% b> 374 cms I2% 3273%8 > by Lynne’ LO OF | grasepun veLune © russ Jofef}}n}o}a} fa} jj fan) OP PPI halla. ots sien | nia owponat | 89. ¢Na (9) SHARON Hs (8) Doe, nadie OF |. fade oof lclonchs ve | Rosier | as of > 19322 | Nh? Hos NHs | niga + 0.8? AO eae thytor tH99 Pelee yoda)romney 4 ge clore a patted pxoriie, Top pousslagess aan. Jo mans oP Pola ae Failed api 2 aticle 5 > ‘ators peers» oonct none A Mote concept gynate= 6-022 410” Salag, Sah pidgestre’2 10. (Ne) , ; nue sor 0% Ee Sipe + Avago wero ;Bue. tateutars at ST. the volume Bf IL 2049 mL - a ROY 2 os. “AEE > mars = 1000 NO. _ looo woth = POO nats Vouume of mole H,) = 22+ 4L= Vn So, Volume of 10¢2 rates H9 W as 4 see = 19-4 X100 > J240L purer. cadeutata the vouwme of 12-DYGAIoCO, vuterubes cut STP. Be yang mada RAIS We Albeo yg Aen “Eee votmmne 04-4 role Wy =29-UL- volume of 2oreote to, 4M “8X11 auen ,coteulose Bre winds of UH$ L ot STP. bo. “ug, , Yolunie., WBE 5 dmb nes” a4 4 molelon 2) iat 32> 44 ras notes aMtxa=! =n na) oun. wich i Lani Ui.) leq 0 (iui) leg ? | aut wos 4 ie of a Gio ee whos 3b4 by pana aa rmole. Ny Wanets ee: DmmotesNHs. Ronin _ Rollie of = Eeethanie ah Volumes gc ue sy i paereare grote Oy —7 role CHY eatin (AA er 4n(39 + aug) —2 Antal) ste 3 ala My AL Ny waaedd vote SL WI? Fh 203 oa dnb uatiin ; WROLes Of Udy amd. HO-forme * Gy D+ 20309), OR, 9 ‘Srwole CHy —arnle 0 anole cif ota] Aywole Uy + male Pr Yynle Cy? Ymole Or jrnple Ry Paraben Hin? gmole Hy > gmnolesH,O atte a rae soy. AO +20,(9)— Fes04oa = sii 5 sities 44144 Bucs rolowtate tne rndler oF 1, ¥ 09d. t) comp Letbyreorct | volte : 284M). Ago, vatesdade Le ie, NH3 paved ul 4 Be Re | He deb ici a Np (8) + 34,9) — 2NA3(49 jue weraponent verricls Cts, Jag in, = Smolen ie? peat ; 4 mole N, —> 3 rwple y= 64 W isdn which wo prune Line Lrmole Ny —> 2mole NH3 wo enalas tina * agian ‘the 900% Za Ebuom 22 Bue [ences Ef). attg + prion of od fovmud. aunos . vateudare doe volume dn Bf Wp | tp eect Rs 2 swcuced ot STP | Bern Prarie tp nate Bao | que. em ~ Cote — 6 boy BHF Fi tie Dee a ee iekemt : AOU nee ale » ge rp mers fe soe bt Mea HF mim @ DLR. ai 0 a ae nee’ > Cg Ho zy i i alert 5 AE rule Cy}? 1 > ee De ate ! oye cae. oul Cyhp 284 m0 win gp swat wabhn eee lune og 3 rate 2p = 30 tnd Pind, vila ge ras oy 38 24 ub moles o& AaBr 9 SOREL a. 98-7 OB w dues, mle Of Cache Hybynd 0, 43 a cone oLeurd As react ust form tp (ato a Ae pee ied < 5 smoleisbe RS Suite BL fw. 2Ha(9) + Onlg)—aHOlD Anat Ps ns, nln ee Grgencns seagir?he & Hy ied 5. dd (il mates merce soouyert ft 1 int ko) ‘gmole 422 semeet an AA Swe. 124 vartson 40 atten fo | fs, cabana KY t Jove (lee, Amar Of 0 fe a incuge, cornplel Bagh, VM) Calcurtate:® "i MenUtiew Or es ae succesion] produces L506 09 0 eee au Kea cuct Dept Taxernpel ikiow of Se 2 OF Wo, produced. at SIP wb 19g C= 9 molec Ct9 + WH eg) ay (WD) fs ha hy 4 Giy begets vy Vor, Bay. 4 mole —s 4 yuste 0, mot dma -4 mole Motes tort 29 drole Jrole 6 — dynole wo, Smole to, = fi} Ov) Males 64D, 3 4 vuole doh lo, = d9yL Ques, coloutare tre vewwme 4 120(4) “dnl produced sat STP pa eae conmatabtion, of Umple Ww) fis. Cats 450, — 302+ 4H,0 synole Cs — > ‘Hrnoleds 4 muate (He —> 2ownledy QH,# + 0 —2QKo 4 male d,—? 2Molet,9 80 rvdleo , > Homusleth© nile 102 23.4 L dup madle Figo > Wox 32-4 D 84a sD A KCLOg xt +302 ole KO, —2 Syyale Or Saas KUL 3 & mole D> CaHy +30) — b Oy TAH ees mole e244 6 ynole0, > Lrote Coty A mole C24 7289 Amale GHy = Sep creat alee sample 0.4 - RE purudy of Pato, 29, +20 “ooy (lds, 2 UNG Oe to, —> 109 cal 14 Oy a, . ooh a> ala HeuNg (0, 44 C02 Ah 2 Od 85h ee crs 5 ae nbs L XEWun Find sie compuurt Bf 80% pure D Waow pega. 40 sect > Wit 21.3.4 clo wine. Ai > ENMOH + 301, —> Gnade + Neblds + 34,0 943.4 0, —> 2udHy Re $q Uy 7 248 g NaOH Da aa3t : 21.34 hy) —p abe x 240g NAOH is et 21.34 Ct, —> 249 NaOH 244. NAOH — 807, HH ayes 80 xy loo a> Dries 5 a= 309 AO Requined ovnudunt OF 207 pure NOOA ie 204, suena ne I A FS a 5 = Ene quucs. 204, ta03 io ended 9 ia “tan amd Wp five volume of 2 ad STP fw. ata, cola 204 2073 moles K tts — > smele bor eA Nace —— NO Wh QI, 2-9 Nay +602 + H0 20.664, SEN Fi b0 2) mole NaH og | Srmole to, >? | roles NAMED, oon a E00 ; x = 9. 2) mes Mts « BBY = 9.52.4 loo | um og = 2.521 | Nate = 4- (2.82) = 1489. Pempastien — 9.52x100- 637, roe Naty "a - ¥, eyikiOw [.4R X100 = 34h rnb iu 4rnble Wo, = 224L 1 bles (0, = BAHL 2 HB 5 egPassed tuo, cues . cadeuctocte Be Ware at harman product. Foswwie cid = HLH Omalic: acid = COOH _ 6H, OY COOH 4m ncoor Se "corgy ,0(0) Cea) OHO 8S, Cog 4 H,0(0) I Oy (Aad {COD Lol) ie we eat plies 2. Teg lh) : Hood ——>! co, + H,0 Hog HCOOH —s 9840 2.34 HWOHK — a5 x24 21% We lo Da eg(iid ie (21047) Oj + a + HO 90. Coty 7 284 CO aM Sq C404 498 xUs . py | 4} igo [Me Whlgnt of somelning- product =14+14 fed delement x ond fovms AY, avd Kaa « Od ole OE XY, WHGhd 10.4, amd 0.05 mole Of Kaa weighs 24. valeulite tne Adore weeds x pnd Y, i fino. 9.4 mole Y, —> 10g 2 to = 10 4 mole XY aa pA 4 mole= 1004. : Amolecule = 100m fe RY,= Wow sindigi Ce ene ee ote vein aaa ’ 0.05 mslersa 2 16 dole ays = ax¥e$ 72 80g prsbecutn wel of No = ye 3a 2 (eM) = asian ed ual XK MAY bee % ame Ae Wapheri uly Twn, 2 Fog eqli) re He oy 24pou. ——e4 44) Foom 4 Cid : 3+ Dy = 20H — alt) Using Unranading, (Seer Antdys Bom =I “pe ane 2m = go now omnal y 5 80, frome welait of x =You Axon. wolayt of Y= 80m | ues, Wd whieh of Ae | fellnaing Anh WOK. WO of chon? 2319 Of Ng bY A 4 6f Op ie) 44% Bb a) 44-04 a preedyon, Vode ued. Cedoutats vwoens 84 LO predted by eating. Of 299. oF i = JBN Y elie (od, —2>—> «oo + ly, Iooq teks —> ug toy Yq Cong — WX4s ieee ith Co, Too tO ire) ae bs aleined aa ge couctlt)in s004p ap solucion” fq. Sy [3)4" acl sot™ 3 5q Nat daw 3004 og, sotucion 254, watt in 48.9 sound (142). 100 ion) mW) eg. tory. (v/v) adeonat 260" a yowl adeeinet aw 190 ms t im > jornl abeatrot im a0 vol : *h(V/V) = abite (AD, 00 Ei mn) 00 % (8) Gt io Apined a raion toownl Of s otlat 9 eels) sotuelon’s 218 J+ (WIN) HyS0y Sat 7 204 804 4m 100m Sia BeSee ec boeebbbecetititicecsg Soldion - | % (Ww> Wve SSS. ae solute), p00 volume Sob (ML) “pom aleewual Jo phuneit gn 4o mH. cabeuoset Its (W/V), | py, eouuie= 20m on = 20+ 40 =bome ‘golution) Dee Ee Xp si, bet tts ny tngt eee ee o 3 a iF gee a Nyt hate Bch 2 ponte Ka trp tre =! win, value ‘on 00» Jo Ab ie eal as OU, QUE, 2h 1,0, 180 tha ida lank posse ploded. tynkaimnen,, caloulads ie cach, verwyppernett, wy. 10 = abt. amotesay 0, te n& = 5 Bue oteutat mote fraction a cavcle COmpenud present in 40% (12/t0) Oy. Lereq 66L™ (UALA2 NH WNH) Riss. 40"/-((apta) 2 409 Sita, ba 1009 600? D40G use im 604 1,9. YOq ared= BE erupts Ure Jo molesH,o X38 TAL roles = Jo +2 = 1 4 ha iH 60g 420 = a1 =osb Xeno? So ZXL ts a ee 6 Rorled Aut, Tf mole prackon of qeaeoie tn 5 y ‘coqudion 20.5 tolowlate | pris lg m 7. (WI). fy. pote o- Sole of afuscade 0S yale quLcnie = BOE, > 00% jmbte sol" = o,Symsle 0-5 Yole wxB- 4 sie i a t § ynplesol = 9049 7 49 4D, a fied 298X100 - 9.409 +2 (Ms) 9a ; | = ; ws 25. = 0.832083 | Xu Poe = 0 | puctiow os ston pa) Pao parr multion (bpm) jwed Ab vocight at Ete pruserct dndog CF Coluxion, = lak e Mobi a0" a her'ta) Uv) Pasets par bilien (ppb) Woigink Jog clude (4) past | dnt ‘SBLudin- Peo Pe) ri ‘at! US aR nena) Me ‘a DS iamudcd prinub oy. ppm ev ppb. ogeaength rae wwlude (3p) -prtserc.bw LL of tolution”, unit = cat) & LT. 4. Sal" souutior AS % ‘im SL olution “Tuma Tum. Ld songs = was 6 oie (0) a VOLUME of BOLCKOn() copeulate 1 of & Sina whi 3429. Cuore jo praserct Am SL sotuibw, eet. 6845" Senength. sot wistiebat ae “r on f ' : of Vole_ 2 SESEeErerererrrrr eee ws Que tntowtatr mote (action & tae. OMmporesce pHuesent, nm 204 cu Eg + 204 sou 3L volume 6 spl" =4L Mas) OF Ufta= 204 rose Of Sale a devathy ~ veeme Sal" 229) a OE me SL wy mass = 2 0ooml 4 dyn mods o¢-L0ln Lit: = 2900 19809. mass Of H,0= 1980 votes Of Hy0 = L392 ornate Motes Of Uren = 86 2 moles be 3 TROL ploy = be eee 3 = 10%} 335 KS Ones Xn: 332 332 16 xe = J Kove Beale 166 ue. coreulate’/, (Wo) vor & Solution te wrose st! do 101. fw. Io L7uqenny 4b Sabu im ALSO mass of souse(s) 4100 ‘lady Sat) 2 A0ON= neo aE) dpoomL = + Y (WIN) > I wae a aaodd Area Louie’ (penstty of L6U"=24ntl) at Ao.dlegimed. % eel (mw) timed. cn WEES OF SU | pIldent in Aig OF SOWUent » | Matabity = ana ) | yyit 2 owe ng! oh rnetad(7) aed ; | peep cesouton 1%; ous op neem iH? ths molality % (2 | mens A a Porecat gluse ave prunent dm 009 Mh = oles So 2 WE ysi900 poh 5.5 suo oe aga es 5 ety 4y gopivved Aud no salu, ust inser ee vik = ywolla/L = instar bie salute wedi « ac an" Hafod Fi a bya ate do TpYempt yen veLop so? Pear naberity | Xo ale ’ nator tty Tenp. “Oud oy “ity” am malay’, Motels so dss Uae ob dk Ad temp. Lnebepenaont Ba. “lo M" S04 cal" DO rroles Of H,S04 im aL soutien > Ratution, (9 Swotartty” amet “strength” vb . x LOUe > yuoled op cote = mobos eT Aes, corteutor ity oy a tol Am votriol. 10-4 NOOK MP) at 200mL- af 7 fy, oq NOOK = Bal oa ' Be 5 = 3.95M Matoutty = Be U aur y 2m NaOH Seve dene a3 ge? Duy, LM NOOH SEA = Dyngles Naot dae LLGal™ mous of sel” demuity of $0” Taro of cat 2 DSA oy mnont = INI9O7 2 On = 1009. raw of NADH = 40 x7 2004 0 & Urt= IIN)-8 0 =fo2 0 on — Moleeipouite, _ Xx1o08 d tn oe ig mete Loy cat = pa, Herciseoney anos tee | voulrne of COU" 1L Yast Of SOL": vourne rd ensity > l000d gaw madd 6 co beent = TAs Bf dol | wae of polute natal coup) fuseiytn)- Ma 2 2 M X 1000 40008 ge -(M AMM gm | 2 molality -_1000M (s006d - mana) | Sibley Df Hy0im 41140 Voluyne= AL donatty = ft. MOM > LE x tovomd = lovee wwe moles 6 Hyp in0004 = [bes S00 sotwmlariny= $02 seem 4 DUPER BBGBAe eee e eee eccecann.Salr Volume = V4 (rales) uti MAM note bagyty > Maa Aidution tuore is ne cnange im coluh. 2 (ULE a (MBL Igafucte Cusion, a rie = [Mala = ava] Mails fsbo boysa= 0 OME ee Mat 0.25M N= ee aed ceurrne peldedl a Ve=4L 5viz IL YA HSL Bub Oe Ma dul sts eine. | aug, Vatewate the final Ht ions sv SOU" Wun 200ml , AMHOL ama 200mL 4M Hsu and) pte HO Ade an = 4X70 - | mile = 0: aes yes SEGRE Hit (nidter) = DeDAL > 0.2 males (maler)psoy = AXE? > 02 moles (rbley)ye = 0-2X2 = 0-4 bled (mbtes}y,0 “PAD HAO do @ wore » i sues nit tala of + Jonas (ON+002 = 0-6 eles matariity (Wies)> Oe ee 0.6M Es a