chemistry presentation (viva)

7/26/2019 Chemistry Presentation (Viva)

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STPM CHEMISTRY 2016THEME: Chemistry in life

Class: 6AS41) Tan Wai Liang [Leader]

2) Tan Jin Yee3) Tan Zi Hong


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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


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"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$


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'()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%


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"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$


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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!


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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.


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-,.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


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/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.


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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


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E&eriment I

THE EFFECT OF pH ON RATE OF

CORROSION


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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


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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.


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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.


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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 ""' "'!! +!!##


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ra&h


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"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.


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E3PERIME4T II

THE RATE OF CORROSION ON

DIFFERENT METAL


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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


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



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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.


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


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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%*# !!*


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ra&h

T#e ra!e o "orrosion agains! !&e o $e!al wi!# olis#ing)


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"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.


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"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.


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E3PERIME4T IIITE !ATE "# C"!!"S$"% "% &$##E!E%T

META' $T "$&E 'A*E!


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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


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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



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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.


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


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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


31/41

ra&h

T#e ra!e o "orrosion agains! !&e o $e!al wi!#o%!olis#ing)


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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.


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"e(!ction


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"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


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"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


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"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


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"e(!ction


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"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


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"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


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"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.


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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.

chemistry presentation (viva)

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