This experiment investigates the corrosion of iron when exposed to various aqueous reagents and metal couples. In Part I, iron nails are placed in different solutions and observed overnight to see if any changes occur. In Part II, an agar gel is used to bring iron and other metal strips into contact to observe any reactions between the metals over time.

1. > e-ps
Chemisrqy 3:
SOME INVESTIGA'TIONS INTO TI-IE
CORROSION OF IIION
Ptocedure:
Part I. Reaction of Iron wirlr Variorrs Aqueous Ileagents
a' Place a cleatt, bright nail in each of the nl.i.*r rrrbe.s. .slicle each
care{rrlly
down the side to avoid breaking the botton, 'ail
oft,ir. tesr rube.
b. Partially fill eacrr of trre rc.rr rub"*s *irh ;;.';i rn. r"rr"*i,if ,.rg",,,s s. thrt
rhe nail is just covered. Your teacher
use. Allsolutions are 0.lM.
will ,.iLyou which ;. ;i1i,;;rorrps ro
KOI"I
[r,PQ,
&€9,*. l&s"!I
HNO
Distilled water
c' Determine the approxitnate hydrogen iorr
corrcenrration o[:eac6 .solution
using litmus pape'; Flydrion-papei or otrrer
iiiai.r.o, soruriorrs. It is
sufficient to recotd siilrply *liutir.ith.
r;il;; is acidic, basic, or neurral.
Go on to part II.
d' Allow the nails t'sta.nd overnight in the solutions. observe
and recor4 any
changes thar have taken place.-(..omparc
1rou,. ,.r,rtrs rvitlr rhose of s...rcle rrrs
using the_1ther sets oFreagenrs. Recorcr
d-,.i,1 ,=rrrrr rro,,f *iirr,-r",,*;"
tabular fornr.
e' After the soltrtiotrs have stoocl nvernigh_t, arld o'c or rwo
. potassiunr fbrricya'ide,
clr.trrs ,:F0.11.4
KFc(CN)., i"l,;.1, conrai^$ rhe ir:rrr.s l(, ;r.cf
^ f"J9N)0."', to each solution ,n,l o'dse*. ,r;r,-l,r,,g*.
f' Add one
4lop oro.l M potassiurn fbrricyani<Je solution r' abour I rnl-
fe*ous strlfaie solrrtio'. c.rnpare ,hi- of ,
;;J;o il,r, obtairrerJ when rlre
. potassium ferricyanide was adied to
the various sol,rtion,, .",,rri,,i"* ,r,,;l*.
vhat concrr-rsio's can be made nor" ii," ,;;;;rr;
in step e?
Part II. 'Reactions invorving Merar coupres
a'Prepare
-'fwo Metars irr colrracL
nrL of agrr-apyrr sorurior,,i, fniluws:
"!!::l.ro1,
of distilled water t. a gentlJboil.' Remo".
Freat arrorrt 200 r'r_.
irt" iu,,,,., a'cl srir. itr 2 g of
powdered agar-agar' dontirtrre the
heating."a .t1i1 rrntil the :rgar- i.s clispersecl.
b. Add about iO arlp, of 0..1M potassiurn feiri.yanide
ancl5 drops o[0.]%,
phenolphtharein indic*ror ro ,t,.
c.
;qir;;;'r"ii;;,,. stir r horougrrry.
Mrile the agar-agar solution i, .ooiirrg,"1,r.p;.
L,,r crearr brighr nairs as
shown i.
Figure la4- Place one nail on one
side of a perri dish or.sr'all
beaker. Bend another nair sharpty *i,h';;;;i,
pr;.* arrrr ir on trrr:
other side of the dish. Twisr. il.rn pi.."'"r.t "i
irJ rnop.r.,ryirc arourr<J a.rhircl
'race
,t
ii
1i
t ,.1

2. i
u
i
.,1 t
I
t*I"Il:ll;#l:',the nailand tighten the wirrr
rugrr' ir rnakes tight co'tact
wi'e c--oir so rrrat wrrerr trrc rrair
prace trris
i.s
second dish. the wirc. irr a
Repeat the above procedure
using a zinc striP .n a fcrrr*h rrail.
zinc is not avairabre, apiece
or-orry rin. nr"y rl"l,r".j,.a by fbrcing srri, oflf'a
through the zinc pie.ein
r.r.t.*o pfaces. i,r,,.. ,rrir',rair irr rrrc trre riair
a's 'show' in Figure jg-i.
", seiorrrl
ff#lu B" r,,r. tr,";^rir',il .or roucfr
o'e
d" $rhen dre agar-agar solution has
cooled to lukewaflh, and
carefrrlly inro tre petri di.she.s is still fluicl,
of about 0.5 crn.
;;rift"
!'v nair.s a.t r,erars a covered to ;ro.r ir
rrdrrit altq fl)etals
are a. ,lepth
e' Make observatio's during the time
remaining in dre crass peri.r,.
6i't'o toly:t:t(er ."1H;; rru,n *goi,ior,., ,i,.f i,ru.
l,racc thc
.stoo<l over'igrrt.
'<-r Zinc slrip
ttt,/
t-
Copper
1 57 f] Y
/'
rv[re
lt* lf ff/
57
t,.
rfr lf
il
',rl/ I
/
khn 1. /
-,{ Pe tfi dishe.t ***,)r_*_=_--**_/. ,/
! l" |
Figure 38 * I
Questions and Exercises '
l' List the teagents itt Part wherc
2' List the ..ri.nt in part rI i;' ;il; no indication of corrosiolr rvas o[r.serverf.
{;-;;;;, iri,.r,,"n
r"'*ii'"*i !/hat i, ,i'. .'ia-'c;e 'rcorrosi'rr.
]
4' -fr',i1""-"ilJffll.';ii" itlg
what did vou observc regarcf
r Fr.r,v clo yc,tr accorr'
the.rcacrions at dre hearJ,
sharp bend of the n';t
*li;tl'
in terrns of tbe rnechanicar
*3.. ainru*r.;;, ;i#:st of poi,rt*,r errcr, or at rrrc
trre
ir."**, rhi nair? Acco..t firr rrri.s,
,
j ffrfi l',illl, #h;tklt**;il$iklixiltrr of the nair during its nranufictrrre.
i,,,,
',t;t;;
; ;,",e an d,,r,
j1frltm ;f**#iu'i'r.il.r",,ia.,1 an' a cororecr precipitate vrire
I
: Fi:li:i:Ti:::**mTffi:LJ;im*x,,.,.,in,,r
;;;;ol'l.*.,ion,
vrr,i.,,,he si,e or
r";;;;h;;e
: consult table ";'i
9' &nn";:ll.;i" dre E" irr Appenclix s
in whicrr yo,, obscrvecla I
p'edicr anorrrer',merar
iron "id that i.s r'ore rea,iry
'"a *iri p,"t*, ;, ri"l" .";il.,:' %sr your. p...ri.rion'by
I
,
^ $J*;1than
l0' How does a coating of
zinc'rt iron (galva'izecl iron),
.,,
I l' Magnesium metar
i"a'r,. ,"*.ori; ptr..J in l;;;i;#;, ir'' fro' corr.sioni
fi
pro(ecrt
rrcaters. wrr'i E
I
I
,*