ferrofluid teacher manual 2005

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Synthesis of an Aqueous FerrouidVersion 3.0

The California NanoSystems Institute & Materials Creation Training ProgramUniversity of California, os !ngeles

S"ien"e #utrea"h Program

$oris Chun, Steven %arlen, Chris %olo'ie(, )o* +ost,Sha*nam Vir(i, Mi"helle ein*erger

November 2005

OverviewStuents -re-are a ferroui / a liui that "ontains small -arti"les, a--ro1imately 20 nanometers iniameter, that s-ontaneously magneti'es in the -resen"e of a magneti" el / through solution"hemistry materials.

Outline Tea"her Pre4a* / 50 minutes

Pre-are solutions of 5M 6eCl5, 2M 6eCl3, an 0.7M N89#8$istri*ute Su--lies to or: !reas

Stuent Pro"eure / 97 minutesSynthesi'e magnetite nano-arti"les from iron "hlorie an ammonia

Isolation of the magnetite nano-arti"lesSta*ili'e the magnetite ;ith tetramethylammonium hyro1ie#*serve s-i:ing

Tea"her Post4a* / 20 minutesColle"t, neutrali'e, an is-ose ;asteColle"t Su--lies an Clean U-

6or the latest u-ate to the manuals, visithttp:voh!"hem!u"la!eduoutrea"h!php#

$is"ussion *oar -ass;or< nanoor email< tolbert$"hem!u"la!edu

%alifornia State S"ien"e Standards &rades '()2Addressed by the Solar %ell *+periment

Teacher Manual Last Updated: 2/22/16 UCLA—CNSI 1



,hysi"s

1m. *Students know how to solve problems involving the forces between two electric charges at adistance (Coulomb's law) or the forces between two masses at a distance (universalgravitation).

5. *Students know electric and magnetic !elds contain energ" and act as vector force !elds.5f. Students know magnetic materials and electric currents (moving electric charges) are sources

of magnetic !elds and are subect to forces arising from the magnetic !elds of other sources.

6erromagnetism is the -ermanent magneti" i-ole that results from the alignment of un-aireele"tron s-ins in elements su"h as iron, "o*alt, ni":el, et". In this e1-eriment, stuents ;ille1-eriment ;ith a ui they "reate that e1hi*its ferromagnetism. They ;ill synthesi'e magneti"nano-arti"les from iron "hlories an is-erse them into a tetramethylammonium hyro1iesurfa"tant to form a "olloial sus-ension. They ;ill then stuy the *ehavior of this ferroui in the-resen"e of an e1ternal magneti" el.

$is"ussion uestions3, 9, an 7 relate tothe "on"e-t of

Coulom*=s a;,;hi"h es"ri*es themagnitue of ele"trostati" for"e,re-ulsion orattra"tion, *et;eent;o "harge-arti"les at a niteistan"e. Thetetramethyl4ammoniumhyro1ie surfa"tantuse in this

e1-eriment is"om-ose of t;o"harge s-e"ies,>C83?9N@ an 4#8. The hyro1ieanions ahere to thesurfa"e of magnetite-arti"les, an thesenegative "hargesattra"t their "ounterions,

tetramethylammonium "ations, forming a -ositively "hargeouter shell. Sin"e li:e "harges re-el, the ele"trostati" re-ulsion

*et;een -ositively "harge outer shells -revent magnetite-arti"les from agglomerating. This results in a "olloialsus-ension of magnetite nano-arti"les, ;hi"h is ;hat ;e "allea ferroui. $is"ussion uestion A eals ;ith magneti" elsan ve"tor for"e els. 6erromagneti" materials res-on toe1ternal magneti" els *y aligning their un-aire ele"tron s-ins;ith the ve"tor els. hen a magnet is far a;ay from thesolution, no e1ternal ve"tor els intera"t ;ith the ferroui,thus there is nothing interesting to see e1"e-t a *la": solution.hen a magnet is *rought "loser to the solution, the magneti"for"e is large enough to ominate the for"es of surfa"e tension




an gravity, the ferroui forms s-i:es in the ire"tion of themagneti" el lines. The stronger the ve"tor el lines, thelarger the s-i:es.

Nano -arti"le -i"ture from< )erger, P.B !elman, N. ).B )e":man, %. +.B Cam-*ell, $. +.B llis, !. ).Bisens:y, D. C. #. of Chemical $ducation )''', EA, F934G.%hemistry

%f. *Students know how to predict the shape of simple molecules and their polarit" from &ewis dot structures.

%h. *Students know how to identif" solids and liuids held together b" van der aals forces or h"drogen bonding and relate these forces to volatilit" and boiling melting point temperatures.

5a. Students know the observable properties of acids bases and salt solutions.

+a. Students know the de!nitions of solute and solvent.+b. Students know how to describe the dissolving process at the molecular level b" using the

concept of random molecular motion.+d. Students know how to calculate the concentration of a solute in terms of grams per liter

molarit" parts per million and percent composition.

The formation of ferroui involves various ty-es of for"es that hol the iHerent "om-onentstogether. #n the mole"ular level, magnetite >6e3#9? is hel together *y ioni" intera"tions in the"rystal latti"e, ;hile tetramethylammonium an hyro1ie are "ovalent mole"ules hel together *yioni" intera"tions. Ioni" attra"tions *et;een hyro1ie anions an tetramethylammonium "ationsena*le the "oating of magnetite nano-arti"les, ;hile ele"trostati" inter-arti"le re-ulsions amongtetramethylammonium "ations allo; "olloial sus-ension of the magnitite in solution. ithouttetramethylammonium hyro1ie as a surfa"tant, magnetite nano-arti"les ten to aggregate ue to

van er aals for"es. Therefore, it is "riti"al to have the a--ro-riate surfa"tant to sta*ili'e anaueous ferroui. In this e1-eriment, stuents ;ill learn that these for"es are res-onsi*le for theformation of ferroui.

$is"ussion uestions E, G, an F eal ;ith *asi" uantitative "hemistry in ;hi"h stuents -ra"ti"e*alan"ing euations, etermining o1iation state in metals, an "al"ulate solution "on"entrations.Stuents "an also -ra"ti"e ;riting out the e;is ot stru"tures of "hemi"als use in this e1-erimentto ientify their "harges, for e1am-le >C83?9N@ an /#8. $is"ussion uestion 20 eals ;ith the-a":ing an layer seuen"e of magnetite in the "rystal latti"e.

-nvesti.ation and *+perimentation

1b. ,dentif" and communicate sources of unavoidable e-perimental error.1c. ,dentif" possible reasons for inconsistent results such as sources of error or uncontrolled

conditions.1d. ormulate e-planations b" using logic and evidence.

$is"ussion uestions 2 an 5 aress the im-ortan"e of aing ammonium hyro1ie at a slo; ratein the early stage of the e1-eriment. In orer for magnetite -arti"les to remain in sus-ension theiriameters must *e on the orer of 20nm >200? or less. )y aing ammonium hyro1ie slo;ly, one"an ensure nanos"ale -arti"le formation. If ammonium hyro1ie ;as ae too ui":ly, large




"hun:s of magnetite ;ill form instea of the esire nano-arti"les, "onseuently the e1-eriment ;illfail. To;ar the en of the synthesis, it is im-ortant to e"ant e1"ess liui out of the ferroui su"hthat it has the right vis"osity to form s-i:es in res-onse to a near*y magneti" el. If the ferrouihas too mu"h e1"ess liui in it, it ;ill not form s-i:es. 1-eriment ;ith the ferroui *y -la"ing themagnet uner the solution. If no s-i:es form, "ontinue e"anting until the right vis"osity is a"hieve.




/////ip for ea"hers/////

Read the entire teachers manual before you begin this experiment with your students! There are a num*er of ;ays in ;hi"h stuents may *e assesse on this e1-eriment. Jou may "hooseto assign some of the is"ussion uestions from the stuent manual for "reit, you may as: thestuents to :ee- a la* note*oo:, or you may as: the stuents to -re-are a la* re-ort.

Ferrouid Supplies 1ist

eusable Supplies -n"luded in 3it:• 90 Safety Dlasses• 570 m Plasti" )ottle• 257 m Plasti" )ottle• 5 Plasti" +ug• 200 m Drauate Cyliner• F >20 m? Drauate Cyliners• KE0 >270 m? Plasti" )ea:ers• K300 arge eigh )oats• K200 Pi-ettes• 50 Magnets• 2 Stainless Steel S"oo-ula S-atula• 3 -: Dloves

%onsumable Supplies -n"luded in 3it:(/eorder reuests0 http0voh.chem.ucla.eduoutreach.php)

• 700g 6eCl3LA85# >6erri" Chlorie?• 500g 6eCl5L985# >6errous Chlorie?• 700 m !mmonium 8yro1ie >5F?• 550 m Tetramethylammonium 8yro1ie•

700 g Citri" !"i• -8 -a-er

Supplies to be Obtained by ea"her:• $istille ater

*a"h &roup of 2(5 Students 4ill Need:• 3 Plasti" )ea:ers >270 m?• 2 Pasteur Pi-ette• 2 arge eigh )oat• 2 Magnet




ea"her ,re(1ab 20 6inutes

,repare the Fe%l27 Fe%l#7 and N89O8 Solutions

The em-ty 570 m *ottle ;ill *e use for the 2M 6eCl3 solution. The em-ty 257 m *ottle ;ill *euse for the 5M 6eCl5 solution. To -revent o1iation of 6eCl5, minimi'e e1-osure of 6eCl5 soli ansolution to air *y :ee-ing *ottles "a--e ;hen not in use. The 5 (ug ;ill *e use for the 0.7M

ammonium hyro1ie solution. T;o liters is enough for 90 e1-eriments. If over 90 e1-eriments areneee, use a larger "ontainer if availa*le, or s-lit the solution into 5 *at"hes< -re-aring the se"onafter the rst is "onsume. The e1-eriment shoul *e one ;ith 547 stuents -er e1-eriment. Thetea"her ;ill etermine ho; many e1-eriments are reuire given "lass si'es, stuent attention, antime. 6or solution -re- "al"ulations, aing e1"ess e1-eriments >K20? to the minimum of e1-eriments reuire ;oul *e a goo iea, allo;ing for s-illsO a""iental overuse of "ertainreagents.

)6 Fe%l#: 2.0G23 g of 6eCl3LA85# is reuire for ea"h e1-eriment. Therefore<

of *+periments ; )!0<)# = &rams Fe%l#>?82O equired for ea"her to 6easure

6eCl3LA85# solution reuires 9 m of ;ater -er e1-eriment. Therefore<

of *+periments ; 9 = m1 4ater equired for the Fe%l# Solution

26 Fe%l2: 0.3FEA5 g of 6eCl5L985# is reuire for ea"h e1-eriment. Therefore<

of *+periments ; 0!#'@?2 = &rams Fe%l2>982O equired for ea"her to 6easure

6eCl5L985# solution reuires 2 m of ;ater -er e1-eriment. Therefore< of *+periments ; ) = m1 4ater equired for Fe%l2 Solution

0!56 Ammonium 8ydro+ide: 2.AAAE m of "on"entrate >5F? !mmonium 8yro1ie is reuirefor ea"h e1-eriment. Therefore<

of *+periments ; )!???@ = m1 %on"entrated Ammonium 8ydro+ide equired for ea"her to 6easure

0.7M !mmonium 8yro1ie reuires ilution to 70 m -er e1-eriment. Therefore< of *+periments ; 50 = otal olume to Bilute %on"entrated Ammonium 8ydro+ide CADords 0!56 SolutionE

Bistribute the Supplies




*a"h &roup of 2(5 Students Should 8ave:• 5 Drauate Cyliners >20 m?• 3 Plasti" )ea:ers >270 m?• 2 Pasteur Pi-ette• 2 arge eigh )oat• 2 Magnet

Set p Fe%l# Station 4ith:• 570 m )ottle of 2 M 6eCl3• Several Plasti" Pi-ettes

• 9 Drauate Cyliners >20 m?

Set p Fe%l2 Station 4ith:• 257 m )ottle of 5 M 6eCl5• Several Plasti" Pi-ettes

• 9 Drauate Cyliners >20 m?

Set p N89O8 Station 4ith:• 5 +ug of 0.7 M N89#8

>If time is an issue, this station "an *e -re4-oure 270 m *ea:ers of 70 m 0.7 N89#8?

Set p inse 4ater Station 4ith:• $istille ater >NO Ta- ater?

>If time is an issue, this station "an *e -re4-oure 270 m *ea:ers of 70 m 85#?

Set p C%89E9NO8 Station 4ith:• 570 m )ottle of tetramethylammonium hyro1ie

• Several Plasti" Pi-ettes only use these -i-ettes ;ith >C89?9N#8Q

/////ip for ea"hers/////

hen -re-aring the 6eCl5, 6eCl3, an N89#8 solutions ;e re"ommen -re-aring an e1"ess 20, this

;ill allo; for any s-ills or a""iental overuse of the reagents that might o""ur. The four solutionstations shoul *e in iHerent -arts of the "lassroom, this ;ill hel- to :ee- a o; to an from thereagents to a minimum. !lso, if time is an issue, -re4-our the N89#8 an istille ;ater into *ea:ersfor your stuents.

Teacher Manual Last Updated: 2/22/16 UCLA—CNSI



Student ,ro"edure 95 6inutes2ote0 3rocedure contains more detail and advanced terminolog" than the student manual

Preparation of the Ferrofluid

1. Add 4 !L "# the $eCl3 s"lut%"n &'(''4 !"l) and 1 !L "# the $eCl2

s"lut%"n &'(''2 !"l) t" a 15' !L *ea+er(

2. ,h%le s-%rl%n. the %r"n chl"r%de s"lut%"n slowly add 5' !L "# '(5

M a!!"n%u! h0dr"%de dr"p-%se "er 5 !%nutes( Picture A It %s

%!p"rtant that the a!!"n%u! h0dr"%de %s added dropwise

espec%all0 at the *e.%nn%n.( The students can add the a!!"n%u!

h0dr"%de !"re 3u%c+l0 at the end &the last 1'42' !L) %# the0 are

sh"rt "n t%!e(

3. A *lac+ prec%p%tate sh"uld #"r! dur%n. the sl"- add%t%"n( Th%s %s

!a.net%te( Picture B The students sh"uld see th%s prec%p%tate

#"r! -%th the #%rst dr"ps "# a!!"n%u! h0dr"%de h"-eer as

l"n. as the students add the a!!"n%a sl"-l0 at #%rst these -%ll *e

s!all part%cle that -%ll d%ss"le *ac+ %nt" s"lut%"n(

4. A#ter all the a!!"n%u! h0dr"%de has *een added st"p s-%rl%n.(

5. lace "ne "# the *ar !a.nets under the *ea+er( It sh"uld pull all

"# the !a.net%te "ut "# the s"lut%"n and the -ater sh"uld

*ec"!e clear( Picture C

6. eep%n. the !a.net "n the *"tt"! "# the *ea+er p"ur "## the

ecess -ater( Th%s techn%3ue %s called decant%n.( I# the !a.net

%s re!"ed then the part%cles -%ll p"ur "## %nt" the -aste

c"nta%ner(

7. Add a !%n%!al a!"unt "# -ater and trans#er the !a.net%te t" a

-e%.h *"at( Students !a0 -ant t" use a sec"nd p"rt%"n "# -ater

t" help trans#er all the part%cles t" the -e%.h*"at(

. lace the !a.net under the -e%.h *"at t" settle the !a.net%te(

!. "ur "## the ecess -ater(

1". 7%nse the !a.net%te t-" !"re t%!es *0 add%n. a s!all a!"unt "#

-ater us%n. the !a.net t" settle the !a.net%te and d%scard%n.

the clear -ater( These r%ns%n.s re!"e the ecess a!!"n%u!

h0dr"%de #r"! the part%cles(

11. 7e!"e as !uch -ater as necessar0 t" #"r! a %sc"us #lu%d( 8e

care#ul N9T t" re!"e all "# the -ater "r 0"u -%ll #"r! a s"l%d(

The sa!ple has the c"rrect c"ns%stanc0 -hen there %s n" #l"- "#

nan"part%cles -hen the -e%.h *"at %s turned s%d-a0s and the

!a.net %s re!"ed( It %s %!p"rtant t" ach%ee th%s c"ns%stanc0

*e#"re sta*%l%:%n. the #err"#lu%d( 9nce sta*%l%:ed the !a.net%te

nan"part%cles *ec"!e -ater s"lu*le and -%ll *e l"st -hen

re!"%n. "## ecess -ater(

Teacher Manual Last Updated: 2/22/16 UCLA—CNSI ;

A

B

C



12. Add 1 !L "# the 25< tetra!eth0la!!"n%u! h0dr"%de s"lut%"n

and !% the #err"#lu%d #"r 2 !%nutes *0 !"%n. the -e%.h *"at

"er the !a.net(

13. 9nce th"r"u.hl0 !%ed place the !a.net under the -e%.h *"at

and re!"e the ecess *lac+ l%u%d %nt" an e!pt0 *ea+er as 0"u

d%d *e#"re dur%n. the r%ns%n.( ,e rec"!!end ha%n. the

students use the e!pt0 r%nse -ater *ea+er =ust %ncase the0 p"ur

"## t"" !uch "# the #err"#lu%d(

14. lace the !a.net under the #err"#lu%d and !"e %t unt%l 0"u see

sp%+%n.( Picture # >"u !a0 -ant t" as+ 0"ur students t" *r%n.

!a.nets #r"! h"!e #"r th%s eper%!ent( ?%##erent !a.nets -%ll

hae d%##erent #%eld l%nes(

$%&'( The #err"#lu%d %s etre!el0 d%##%cult/%!p"ss%*le t" re!"e #r"! cl"th%n.( It %s als" d%##%cult t" re!"e #r"!

!a.nets( Students sh"uld ta+e care t" a"%d d%rect c"ntact "# the #err"#lu%d -%th cl"th%n. and !a.nets(

ea"her ,ost(1ab )0 6inutes

%olle"t7 NeutraliGe7 and Bispose of 4asteColle"t the ;aste from all the e1-eriments in a large "ontainer an neutrali'e the *ase ;ith "itri"a"i. #n"e the -8 is *et;een A an 20 you "an -our ;aste o;n the rain follo;e *y -lenty of ;ater >to ensure that all sus-ene solis are ushe o;n the rain?. The -8 "an *e measureusing the -8 -a-er -rovie in the :it, there is a "olor s"ale on the sie of the -8 -a-er "ontainer.

Su..ested opi"s for Bis"ussion

2. hat is the molarity of the 6eCl3 an 6eCl5 solutionsR

2M for 6eCl3 an 5M for 6eCl5.

5. hy o you thin: slo; >ro-;ise? aition of ammonium hyro1ie is im-ortantR hat mightha--en if you a ammonium hyro1ie ui":lyR

The ammonium hyro1ie solution is ae slo;ly to ensure nanos"ale -arti"le formation,rather than formation of large "hun:s of magnetite. Thus, if it is ae ui":ly, large "hun:sof magnetite ;ill form instea of the esire nano-arti"les.

3. Magnetite, 6e3#9, "onsists of iron in ;hat o1iation statesR

#1iation states of iron are @5 an @3.

9. . hy o you -la"e a magnet unerneath the *ea:er ;hile removing ;aterR

In the -resen"e of a magneti" el > i.e. a magnet? the magnetite is magneti". )y -la"ing amagnet unerneath the *ea:er, the magnetite is attra"te to magnet an -rou"t loss isminimi'e ;hile the ;ater is remove.

7. hat is the -ur-ose of the sta*ili'ing agent tetramethylammonium hyro1ieR hat mightha--en if NO sta*ili'ing agent is useR

Teacher Manual Last Updated: 2/22/16 UCLA—CNSI @

#



Tetramethylammonium hyro1ie is a sta*ili'ing ligan that is use to :ee- the nano-arti"lesin solution an from sti":ing to ea"h other. That is, it aheres to the -arti"les "reating a netre-ulsion *et;een them so the -arti"les o not agglomerate. In the a*sen"e of a sta*ili'ingagent the -arti"les ;ill agglomerate. These "onglomerates ;ill then -re"i-itate from thesolution as a *la": soli.

A. $es"ri*e ;hat ha--ens ;hen a magnet is *rought near a ferroui. hat ha--ens ;hen themagnetis remove from the ferrouiR

hen the magnet is far a;ay from the solution there is nothing interesting to see e1"e-t a*la": solution. hen the magnet is *rought "loser to the solution then you see s-i:es"orres-oning to the magneti" el lines. The stronger the el lines, the lager the ferrouis-i:es along the line.

F. !$V!NC$< )alan"e the follo;ing euation.

56eCl3 @ 6eCl5 @ GN83 @ 985# 6e3#9 @ GN89Cl

20. Chemistry "lasses may ;ish to is"uss the "rystal -a":ing of magnetite, sho;n *elo;.5

4his is one of the cr"stallographic planes of the magnetite cr"stal lattice. ,n this diagram there is a ratio of % e 0 1 e% 0 6 78%

Teacher Manual Last Updated: 2/22/16 UCLA—CNSI 1'



Further Biss"ussion4opics for 9dvanced Students

4hat is a FerrouidH

! ferroui is a "olle"tion of su-er-aramagneti" nano-arti"les that are sus-ene in a liui. These nano-arti"les are a--ro1imately 20 nm in iameter. The ma(ority of nano-arti"les, li:e theones you ma:e in this la*, are iron4*ase, su"h as magnetite >6e3#9?. If as4synthesi'e nano-arti"lesare -ut into solution, they aggregate an form "lusters ue to van er aal intera"tions. These"lusters are too large to *e :e-t in sus-ension *y )ro;nian motion an settle to the *ottom of the"ontainer. The use of a magnet "an a""elerate the settling of these "lusters allo;ing for easy;ashing of the -arti"les.

Nano-arti"les ;ill remain sus-ene in a solution as long as they o not aggregate. ! te"hniue to-revent aggregation is to sta*ili'e= the -arti"les *y en"a-sulating them ;ith an outer shell. Thegeneral metho to a"hieve this is to use a surfa"tant. Surfa"tants are mole"ules ;ith t;o"ontrasting -ro-erties. They "an *e a linear mole"ule ;ith a hyro-hili" region an a hyro-ho*i"region, or a "ation anion -air. The former ;or:s *y having the hyro-hili" en of the mole"ulesatta"h to the magnetite nano-arti"les -ositioning the hyro-ho*i" en to form a greasy= layeraroun the -arti"le. This greasy= layer -revents nano-arti"les from getting "lose enough to ea"hother to aggregate. The later is the metho use in this e1-eriment. The ion -air :ee-s -arti"les

se-arate through Coulom*i" re-ulsion *y en"a-sulating the -arti"les ;ith a "ationi" outter shell. The anions ahere to the surfa"e of the magnetite nano-arti"les, an they attra"t its "ounter "ationsto form the -ositively "harge outer shell. Sin"e li:e "harges re-el, the -ositively "harge outer shell-revent magnetite nano-arti"les from aggregating.

Appli"ations of Ferrouids

There are many a--li"ations of ferrouis. Most a--li"ations are *ase on these -ro-erties<2? The ferrorui ;ill go to ;here the strongest magneti" el is an stay there >this is

"alle lo"ali'a*ility?.5? 6errouis a*sor* ele"tromagneti" energy at "onvenient freuen"ies an heat u-.3? The -hysi"al -ro-erties of ferrouis "hange ;hen a magneti" el is a--lie.




6e"hani"al Appli"ations

6errouis are use as seals in gas lasers, motors, an *lo;ers. In these a--li"ations theferroui is hel in -la"e *y a strong magnet an se-arate t;o iHerent -ressure "ham*ers. Theyhave also *een use to as a meia for vi*rational am-aning in ele"troni" a--li"ations, su"h as harrives, gra-hi" -lotters, an instrument gauges. 6errouis are also foun in almost all high -o;erlous-ea:ers. The ferroui is :e-t in -la"e *y the magnet on the horn of the lous-ea:er, anserves to seal the s-ea:er "ham*er, "ool the s-ea:er, an am-en un;ante overtones.2

6edi"al Appli"ations

There is also a su*stantial interest in using ferrouis for mei"al a--li"ations. 6or e1am-le, if arug use to treat "an"er ;as in(e"te into a -erson ;ith the ferroui, a magneti" el "oul *euse to fo"us the rug onto the tumor. #r, a ferroui, on"e in(e"te, "oul *e easily heate lo"allyto *urn a tumor. These methos have alreay *een su""essful at estroying "an"ers in rats.

Other Appli"ation

Perha-s one of the most interesting a--li"ations is in in:B ferroui *ase in: is use *y the USgovernment to -rint the one ollar *ill.5 This hel-s the government to ientify "ounterfeit *ills.




eferen"es

2. osens;eig, . . Scienti!c 9merican )'<2, 59E>9?, 23A497.5. )erger, P.B !elman, N. ).B )e":man, %. +.B Cam-*ell, $. +.B llis, !. ).B isens:y, D. C. #. of

Chemical $ducation )''', EA, F934G.3. htt-<OO;;;.mrse".;is".euO$TCO"ine-le1Oine1.html9. S"herer, C. an Neto, !.M.6. )ra'ilian +ournal of Physi"s, 37, 3!, E2G >5007?.7. #en*a"h, S. +ournal of Phys. Con. Matter., 2A >5009?, 2237.

A. 8ere are some ;e* sites ;ith more information on magnetism<htt-<OOsolar4"enter.stanfor.euOmagnetismOintrou"tion.htmlhtt-<OO;;;.s"hool4for4"ham-ions."omOs"ien"eOmagnetism.htm

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Bepartment of %hemistryniversity of 4is"onsin7 6adison

http:i"e!"hem!wis"!edu

Co-yright 5003 *y Sarah Tol*ert. !ll rights reserveB revise 500E


http://www.mrsec.wisc.edu/EDETC/cineplex/index.html

http://solar-center.stanford.edu/magnetism/introduction.html

http://www.school-for-champions.com/science/magnetism.htm

http://www.mrsec.wisc.edu/EDETC/cineplex/index.html

http://solar-center.stanford.edu/magnetism/introduction.html

http://www.school-for-champions.com/science/magnetism.htm

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