Experiment 6 - Elemental Analysis

ELEMENTAL Sodium fusion ANALYSIS

INTRODUCTION Elemental Analysis -used for identication of unno!n com"ounds -c#ief as"ect in i n e$"erimental or%anic c#emistry

Sodium fusion -also no!n as Lassai%ne&s test -useful met#od for 'ualitati(ely determinin% t#e "resence of sulfur) nitro%en or #alo%ens in or%anic com"ounds -"ro"erty of sodium to *e a (ery stron% reducin% a%ent maes it "ossi*le to *rea t#e or%anic com"ound&s car*on c#ain into inor%anic ions

Sodium fusion -t#e ltrate from t#e fused solution of t#e unno!n com"ound and sodium metal is used to conduct t#e conrmatory tests for t#e "resence of sulfur) nitro%en or #alo%ens

E+,ERIMENTAL Set-u"  T#e set-u" for sodium fusion !as done as s#o!n in t#e %ure.

,ea-si/ed sodium !as "laced in a small test tu*e0 T#e test tu*e !as #eated until sodium (a"or !as o*ser(ed to condense on t#e !all of t#e test tu*e0  T#e 1ame !as remo(ed and a*out 203% of "-c#loroaniline !as added0

 T#e test tu*e !as #eated %ently to initiate t#e reaction !it# sodium0 T#e 1ame !as remo(ed !#en t#e reaction su*sided t#en it !as #eated to redness for 3 minutes

 T#e red-#ot tu*e !as dro""ed in a 42mL *eaer containin% 52-mL of distilled !ater

Solution !as ltered and t#e ltrate !as used as t#e test solution

6T#e "rocedure !as re"eated usin% sulfanilic acid7

8ualitati(e Analysis Sulfur test 9i(e dro"s of fusion solution and 3 dro"s of !ater !ere "laced in a 4-mL test tu*e : dro"s of :; a'ueous sodium nitro"russide solution !as added

 T#e formation of a dee" *lue-(iolet color !as o*ser(ed

Nitro%en test A "inc# of 9eSOM ?:SO?HNO3S - It can *e o*ser(ed t#at t#ere is no #alo%en in sulfanilic acid) *ut t#e "resence of sulfur and nitro%en are conrmed Nitro gen Test

Halog en Test

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Sulfu Sample r Test

"c#loroa niline Sulfanili c acid

CONCLUSION Sodium fusion is a test to determine t#e "resence of some elements lie sulfur) nitro%en) and #alides suc# as c#lorine) *romine) and iodine0 T#is is "ossi*le *y turnin% t#ese insolu*le elements into solu$le so%ium salts&  T#e "resences of t#e mentioned elements are determined t#rou%# series of 'ualitati(e tests mainly *y forming olore% preipitates or pro%uts 0 9lame test can also *e done as a "retest for #alo%en since a %reen 1ame result indicates t#e "resence of #alo%ens0

RECOMMENDATION Since t#e e$"eriment em"loyed only one conrmatory test for t#e "resence of nitro%en) sulfur) and #alo%ens) it is recommended to use ot'er met'o%s for conrmin% t#e elements mentioned0

ANSGERS TO @UIDE 8UESTIONS 50 Outline t#e "rocedures for detectin% t#e "resence of o$y%en and "#os"#orus in or%anic com"ounds0 & O*gen Ferrox Test  -@rind one crystal of ferric ammonium sulfate and a crystal of "otassium cyanate usin% a %lass rod 6do t#is in a dry s"ot "late7 -Add : dro"s of t#e unno!n in a se"arate !ell -Use t#e %lass rod !it# attac#ed %round u" crystals to stir t#e unno!n -A "ositi(e test indicates %issolution of

,& -'osp'orus

-T#e unno!n is fused !it# sodium "ero$ide 6Na :O:7 -,#os"#orus "resent in t#e unno!n is con(erted to sodium "#os"#ate -9used mass is e$tracted !it# !ater -A'ueous e$tract is #eated !it# concentrated nitric acid and ammonium moly*ate solution0 - .ello/ preipitate of ammonium p'osp'omol*$ate (NH ")"[-0o#2O41] in%iates t'e presene of p'osp'orus0

:0 Discuss ot#er met#ods of detectin% t#e "resence of sulfur) nitro%en and #alo%en in or%anic com"ounds0 & Sulfur Using the sodium fusion solution Lead acetate solution is added to t#e fusion solution0 A "ositi(e test for sulfur is indicated *y t#e "resence of a $la preipitate (-$S)& Oxidation test  T#e unno!n or%anic com"ound is #eated !it# o$idi/in% fusion mi$ture 6Na :CO3  =NO370 If sulfur is "resent) it !ill *e o$idi/ed to sulfate0 T#e fused mass is e$tracted !it# !ater0 It !as made acidic *y

,& Nitrogen  Addition of p-nitrobenzaldehyde  To t#e fusion solution) add "nitro*en/alde#yde solution0 After!ards) add a *asic solution of o-dinitro*en/ene0 A "ositi(e test is indicated *y a $lueviolet olor0 Oxidation of benzidine with cupric ion  T#is reaction !ill not tae "lace in t#e a*sence of cyanide ion0 T#e cyanide com"le$es !it# cu"rous ions so as to increase t#e o$idation "otential of t#e system0

C& Halogens Sodium odide in Acetone Test   To t#e unno!n) add solution of sodium iodide in acetone0 S#ae tu*e to ade'uately mi$ t#e unno!n and t#e solution0 If a*out 4 minutes #as "assed and "resence of "reci"itate is still not e(ident) "lace test tu*e in a 42 !ater *at#0 9ormation of a /'ite preipitate indicates "resence of #alides0 !eilstein Test  ?eat t#e ti" of a co""er !ire in a *urner 1ame0 Cool t#e !ire sli%#tly t#en di" it into t#e unno!n0 ?eat it once a%ain0 A green 3as' is indicati(e of c#lorine) *romine)

RE9ERENCES Sri(asta(a) A0=0) 6:22H70 "hemistry 0 Del#i. J0=0 6India7 Enter"rises "hemical Tests for Un#nowns$ Retrie(ed from #tt".KKcactus0di$ie0eduKsm*lacKc#emla*sKC#emicalTest sforUnno!ns0"df  %etection of &hosphorus' Sulfur and Oxygen Retrie(ed from #tt".KK%radestac0comKClass-55t#-Science-Git#-Mat#-KDe tection-of-,#os"#orus-Sul"#ur-and-O$y%enK5H4>:-34>-study-!t! Organic (ualititati)e Analysis$ Retrie(ed from #tt".KKfaculty0s!osu0eduK!illiam0ellyK"dfK'o:a0"df  Test for *alides$ Retrie(ed from #tt".KKacademics0!ellesley0eduKC#emistryKc#em:55la*KOr% oLa*ManualKA""endi$KClassicationTestsK#alide0#tml