of 41
7/26/2019 Chemistry Presentation (Viva)
1/41
STPM CHEMISTRY 2016THEME: Chemistry in life
Class: 6AS41) Tan Wai Liang [Leader]
2) Tan Jin Yee3) Tan Zi Hong
7/26/2019 Chemistry Presentation (Viva)
2/41
What is metal corrosion
Metal corrosion is the deterioration of materials by chemicalinteraction with the environment.
A metal corrosion is a natural process, which a metal will convert
itself to a more stable form
water or moisture in the air
acids
bases
salts
aggressive metal
What ca!ses the corrosion
7/26/2019 Chemistry Presentation (Viva)
3/41
"oes metal occ!rs in nat!ral as P#REform
Most of the metal does not occur in nature in pure form, exceptgold,platinum and silver.
Ho$ to %et &!re metal
blast furnace electrolysis
wwwessen!ial"#e$i"alind%s!r&org
wwwele"!ri"al4%"o$
7/26/2019 Chemistry Presentation (Viva)
4/41
'()anta%es of metal corrosion
Protective layer
Surface corrosion will forms an oxide layer which will protects the
metal instead of being corroded.
Al%$ini%$'(ide
wwwoened%
7/26/2019 Chemistry Presentation (Viva)
5/41
"isa()anta%es*
Reduce the strength of the structure
Causing tetanus
Reduce the beauty or attractiveness of gadget and devices
wwwleoardan!i*%es"o$ wwwreddi!"o$
7/26/2019 Chemistry Presentation (Viva)
6/41
Research +!estion
ow does the p affect the rate of corrosion!
"hat is the rate of corrosion of different metal!
ow does the oxide layer on the surface of the metal affect the rate
of corrosion of metal!
7/26/2019 Chemistry Presentation (Viva)
7/41
Pro,lem Statement
#he rate of corrosion of the metal is affected by thepH medium.#he rate of corrosion could be calculated by measuring the weight
loss of the metal.
7/26/2019 Chemistry Presentation (Viva)
8/41
-,.ecti)e of research
#o determine the effect of p on rate of corrosion
#o determine the rate of corrosion of different metal
#o determine the effect of oxide layer on the surface of metal
against the rate of corrosion of metal
7/26/2019 Chemistry Presentation (Viva)
9/41
/imitation of st!(y
#he electronic balance is not sensitive enough to measure the small weightloss of the metal.
#he time ta$en for the experiment is short.
#he temperature for the experiment is not controlled.
#he removing processof the corroded metal is not standarddue to the
limit of chemical in lab.
7/26/2019 Chemistry Presentation (Viva)
10/41
E&eriment
i. THE EFFECT OF pH ON RATE OF CORROSION
ii. THE RATE OF CORROSION ON DIFFERENT METAL
iii. THE RATE OF CORROSION ON DIFFERENT METAL
WITH OXIDE LAYER
7/26/2019 Chemistry Presentation (Viva)
11/41
E&eriment I
THE EFFECT OF pH ON RATE OF
CORROSION
7/26/2019 Chemistry Presentation (Viva)
12/41
THE EFFECT OF pH ON RATE OFCORROSION
Apparatus% &'( cm)bea$er, forceps, hair drier, sandpaper, electronic
balance, meter rule, scissors, '(cm)measuring cylinder, p meter
Material% *ead strips x ' +&cm x 'cm, (.(- moldm )/0)solution,
-.(1-('moldm)/0)solution, distilled water, (.(- moldm)/a0
solution and -.(1-('moldm)/a0
7/26/2019 Chemistry Presentation (Viva)
13/41
PR-CE"#RE
-. #he 5 lead stripsare cleaned using sandpaper.
&. #he 5 lead stripsare immersed into acetone solutionand dry using
a hair drier.
). #he mass and the area of the ' lead strips are measured using
electronic balance and meter rule.
2. #he p of solution for bea$er A to 3 which contain 0.01 moldm-3
HNO3 solution, 1.010-5moldm-3HNO3solution, distilled water,
0.01 moldm-3 NaOH solution and 1.010-5 moldm-3 NaOH
solutionrespectively are measured using p meter.
'. #he 5 lead stripsare immersed into the ' solution respectively and
the time is recorded.
7/26/2019 Chemistry Presentation (Viva)
14/41
4. #he 5 lead stripsare ta$en out from the solution on the second days
and the time was recorded
5. #he 5 lead strips are then immersed in 0.17 moldm-3 H3OOH
solutionfor ' minutes.
6. #he 5 lead strips are then immersed in acetone solution and dry
using a hair drier.
7. #he mass of lead stripsare measured using electronic balance.
-(. #he data was tabulated.
7/26/2019 Chemistry Presentation (Viva)
15/41
T'/E
Metal pH InitialWeight(g)
FinalWeight(g)
Weightloss (g)
Initialtime
Finaltime
Timetaken
(min)
Rate ofcorrosio
n
(mm/y)
Pb 2! "## "2$ !!% "2&"2 ""$ "'!# !2'
Pb ' "2% "2$ !!# "2&"2 ""! "#% !!
Pb *2 "#! "2* !!# "2&"2 ""&2$ "## !"!!
Pb * "#' "## !!" "2&"2 ""&2$ "'!2 !!##
Pb "" "## "#' +!!" "2&"2 ""' "'!! +!!##
7/26/2019 Chemistry Presentation (Viva)
16/41
ra&h
7/26/2019 Chemistry Presentation (Viva)
17/41
"e(!ction
8raph - show that the rate of corrosion decrease as p increase. #heincrease of weight of lead strips at p --.4 show that lead strip startedto form a protective layer on its surface.
#he rate of corrosion increases as p decreases is due to when metalis immersed in solution with lower p +higher concentration of 9 ions,electrons can react with hydrogen ions adsorbed on the metal surfacefrom the solution to produce hydrogen gas
&!9 &e- + "
#he occurrence of the reaction permits the continues passage of ane:uivalent :uantity of metal ions into solution, leading the faster rate ofcorrosion of metal.
7/26/2019 Chemistry Presentation (Viva)
18/41
E3PERIME4T II
THE RATE OF CORROSION ON
DIFFERENT METAL
7/26/2019 Chemistry Presentation (Viva)
19/41
THE RATE OF CORROSION ONDIFFERENT METAL
Apparatus% &'( cm) bea$er, forceps, hair drier, sandpaper, electronic
balance, meter rule, scissors, '(cm)measuring cylinder, p meter
#aterial% lead strip, ;inc strip, tin strip, copper strip, aluminum strip+&cm x 'cm and (.(- moldm) /0)solution
7/26/2019 Chemistry Presentation (Viva)
20/41
PR-CE"#RE
-. #he lead strip$ %inc strip$ tin strip$ copper strip and aluminumstripare cleaned using sandpaper.
&. #he 5 metal strips are immersed into acetone solution and dry
using a hair drier.
). #he mass and the area of the ' lead strips are measured usingelectronic balance and meter rule.
2. #he p of the solution in bea$er A to 3 which contain 0.01 moldm-3
HNO3solutionare measured using p meter.
'. #he 5 metal stripsare immersed into the ' solution respectively and
the time is recorded.
7/26/2019 Chemistry Presentation (Viva)
21/41
5. ' metals strip are immersed into different type of solution with different
time.
6. #he 5 metal stripsare then immersed in acetone solutionand dry
using a hair drier.
7. #he mass of the 5 metal strips are measured using electronic
balance.
-(. #he data was tabulated.
TYPE -5 MET'/S
STRIPSTYPE -5 S-/#TI-4 TIME
lead,1- $old$) CH)C''H
sol%!ion. $in%!es
al%$in%$ 1, $old$)
/0)sol%!ion 2 $in%!es"oer 1/ $old$)H&S'2sol%!ion 2 $in%!es
!in ,6 $old$)HCl sol%!ion 1, $in%!es
0in" s!ri 1,2 $old$)HCl sol%!ion,2.
$in%!es
7/26/2019 Chemistry Presentation (Viva)
22/41
T'/E
Metal pH Initial
Weight(g)
Final
Weight(g)
Weight
loss (g)
Initial
time
Final
time
Time
taken
(min)
Rate of
corrosio
n (mm/y)
Pb 2! "$$ "'! !"$ ""&$! ""# 2%# !2'2
,n 2! "$' "$2 !!2 ""&$! "" 2% !!$"
-n 2! #"$ #!* !!% ""&$! ""&$! 2%%! !2!"
. 2! !%! !*% !!2 ""&$! ""&'% 2%*% !!'"
0l 2! !#! !2 !!" ""&$! ""&'# 2%*# !!*
7/26/2019 Chemistry Presentation (Viva)
23/41
ra&h
T#e ra!e o "orrosion agains! !&e o $e!al wi!# olis#ing)
7/26/2019 Chemistry Presentation (Viva)
24/41
"e(!ction
8raph & shows that the rate ofcorrosion of lead, %inc, tin, copper
and aluminum metalare different in
acidic condition &pH "'. #he rate of
corrosion of lead is the highest
followed by tin, aluminum, %incand
lastly copper.
7/26/2019 Chemistry Presentation (Viva)
25/41
"e(!ction
=rom the table above, it shows that the stability of the metal compare tometal ion of Cu> Pb> Sn> ?n> Al which is differ from the rate of
corrosion of the metal which shows Cu@ ?n@ Al@ Sn@ Pb.
#he a(normal (e)aviorof the metal are most probably cause by theoxidi%ing o* aluminum stripbefore immersed in the acid and the ;inc
strip is not well cleaned due to the absent of corrosion inhibit specimen.
7/26/2019 Chemistry Presentation (Viva)
26/41
E3PERIME4T IIITE !ATE "# C"!!"S$"% "% &$##E!E%T
META' $T "$&E 'A*E!
7/26/2019 Chemistry Presentation (Viva)
27/41
THE RATE OF CORROSION ON DIFFERENTMETAL WITH OXIDE LAYER
Apparatus% &'( cm) bea$er, forceps, hair drier, electronic balance,
meter rule, scissors, '(cm)measuring cylinder, p meter
#aterial% lead strip, ;inc strip, tin strip, copper strip, aluminum strip+&cm x 'cm and (.(- moldm)/0)solution
7/26/2019 Chemistry Presentation (Viva)
28/41
PR-CE"#RE
-. #he lead strip$ %inc strip$ tin strip$ copper strip and aluminumstripareprepared
&. #he 5 metal strips are immersed into acetone solution and dry
using a hair drier.
). #he mass and the area of the ' lead strips are measured usingelectronic balance and meter rule.
2. #he p of the solution in bea$er A to 3 which contain 0.01 moldm-3
HNO3 solution are measured using p meter.
'. #he 5 metal stripsare immersed into the ' solution respectively and
the time is recorded.
7/26/2019 Chemistry Presentation (Viva)
29/41
5. ' metals strip are immersed into different type of solution with differenttime.
6. #he 5 metal stripsare then immersed in acetone solutionand dry
using a hair drier.
7. #he mass of the 5 metal strips are measured using electronicbalance.
-(. #he data was tabulated.
Snapchat&&7&654(46(7(7&&)54.mp2
TYPE -5 MET'/S
STRIPSTYPE -5 S-/#TI-4 TIME
lead,1- $old$) CH)C''H
sol%!ion. $in%!es
al%$in%$ 1, $old$)H')sol%!ion 2 $in%!es
"oer 1/ $old$)H&S'2sol%!ion 2 $in%!es
!in ,6 $old$)HCl sol%!ion 1, $in%!es
0in" s!ri 1,2 $old$)HCl sol%!ion,2.
$in%!es
7/26/2019 Chemistry Presentation (Viva)
30/41
T'/E
etal + $n,t,al
e,-t(-
)
#,nal
e,-t(-
)
e,-t
l/
(-)
$n,t,al
t,e
#,nal
t,e
T,e
taen
(,n)
!ate /
/55/,
/n
()
Pb 2.0 1.83 1.77 0.06 1292: 10942 2777 0.100
Zn 2.0 1.62 1.60 0.02 1292: 10947 2782 0.0:2
Sn 2.0 3.00 2.;6 0.04 1292: 1094; 2784 0.103
Cu 2.0 0.;6 0.;4 0.02 1292: 10938 2773 0.042
Al 2.0 0.30 0.30 0 1292: 109:0 278: 0
7/26/2019 Chemistry Presentation (Viva)
31/41
ra&h
T#e ra!e o "orrosion agains! !&e o $e!al wi!#o%!olis#ing)
7/26/2019 Chemistry Presentation (Viva)
32/41
Com&are THE R'PH*
8raph ) show that the rate of corrosion of
Al, Sn and Pb have a great decrease if the
metal strips are not polished before
immersed into solution.
#he decreases o* t)e rate o* corrosion
show that the protective layer of lead, tin,
and aluminum is very effective for protectingthe metal from being corroded.
#he protective layer of aluminum has *ully
protected aluminum from corrode and the
protective layer o* lead and tin has
decreased t)e rate o* corrosion o* t)e
metal (y +1, and 51,respectively.
7/26/2019 Chemistry Presentation (Viva)
33/41
"e(!ction
7/26/2019 Chemistry Presentation (Viva)
34/41
"e(!ction
Pb0 is not form in this experiment is due to distilled water was usedin this experiment and the diffusion rate of oxygen into water is low.
#he low concentration o* oxygen causes the formation of Pb0
does not happen or not signi*icant to (e detectedby na$ed eyes.
9ig%re1: Lead$e!ali$$ersed inH 2sol%!ion
9ig%re
2:CorrodedLead
7/26/2019 Chemistry Presentation (Viva)
35/41
"e(!ction
#he lead metal strips sample which is immersed
into solution with pH .+ and 7.". #he 3hp
diagram shows that the predominant species
that will form is (O3 which is an insoluble
white solid. #he carbon dioxide in air react with
water forming carbonic acid, H"O3 which is
then dissociate into hydrogen ion, 9 and also
carbonate ion, C0)&
C0&9 &0 + &C0)
&C0) &+ 99 C0)&
#he carbonate ion is then react with lead+ ion
which is form from the corrosion of lead metal by
water to form lead+ carbonate, PbC0).
9ig%re 3:Lead$e!ali$$ersed in H64sol%!ion
9ig%re 4:
Lead$e!ali$$ersed in H-2sol%!ion
7/26/2019 Chemistry Presentation (Viva)
36/41
"e(!ction
"hile at pH 2.7, due to the higherconcentration of hydroxide ion, OH-,
basic lead car(onate$ (3&O3'"&OH'
"or sometime written as
"(O3(&OH'" is formed which is
in white powder form is formed
instead of lead&' car(onate$ (O3.
9ig%re.: Lead$e!ali$$ers
ed inH -sol%!ion
7/26/2019 Chemistry Presentation (Viva)
37/41
"e(!ction
7/26/2019 Chemistry Presentation (Viva)
38/41
"e(!ction
Bue to the low rate of corrosion of copperand aluminum metal, the product formed is
unable to be predicted. #heoretically, copper
will react with nitric acid to form nitrogen
monoxide$ NO", waterand copper nitrate$
u&NO3'" forming a green solution while
aluminum react with nitric acid to formcolourless aluminum nitrates 4l&NO3'3
and )ydrogen gas.
Cu 9 2/0) Cu+/0)&9&/09&&0
&Al 9 4/0) &Al+/0))9 )&
5l%e
"olo%rless
9ig%re -:Coer$e!ali$$ersed in H 2sol%!ion
9ig%re /:Al%$in%$ $e!al
i$$ersed in H 2sol%!ion
&ellow
7/26/2019 Chemistry Presentation (Viva)
39/41
"e(!ction
"hen %incis immersed in cold and diluted nitric acid, %incwill liberatenitrogen monoxide$ NO, %inc nitrate$ n&NO3'"and water. #he %inc
nitratewill then dissolve in water to form a colourless solution.
)?n 9 6/0) )?n+/0)&9 &/0 9 2&0
?n+/0)& ?n&99 &/0)
#he thin layer of (lac6 soliddetect in the experiment may due to the
impuritiesin the ;inc metal strips
9ig%re :Zin" $e!alwi!#s"r%55ing)i$$ersed
in H 2sol%!ion
9ig%re 1,:Zin" $e!alwi!#o%!s"r%55ing)i$$ersedin H 2
sol%!ion
7/26/2019 Chemistry Presentation (Viva)
40/41
"e(!ction
"hen tin &stannum' is immersed in nitric acid, tin will liberate
nitrogen dioxide$ NO", tin nitrate$ n&NO3'" and water. #he tinnitratewill then dissolve in water to form a colourless solution.
7/26/2019 Chemistry Presentation (Viva)
41/41
Concl!sion
#he rate of corrosion decrease as p increases
#he rate of corrosion of the metal under acidic condition of Pb> Sn>
Al> ?n> Cu
#he protective layer of aluminum, lead and tin are able to decrease
the rate of corrosion under acidic condition but not ;inc and copper.