ELt^,"ffiffiKffiRESEARCH UNIVERSITY

TJNIVERSITI TEKNOLOGI MALAYSIAFACULTY OF SCIENCE

FINAL EXAMINATIONSEMESTER I SESSION ?OLINAIZ

CODE

COURCE

LECTI'RER

SSC 1293

ANATYTICAL CHENIISTRY

PROF. DR. ALIAS MOHD YUSOFASSOC. PROF. DR. MOHD SIIAHRU BAIIARIASSOC. PROF. DR. AZLI SULAIMANMR. HASHIM BAHARIN

SKB/SKK/SKR

9 JANUARY 2OI2

2% HOIJRS

ANSWER ALL QUESTIONS IN THE BOOKLETPROVIDED.

PROGRAM

DATE

DURATION

INSTRUCTION

UESTION PAFER CONSISTS OF 5 PRTNTED PAGES INCLUDING THIS PAGE

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QUESTION I (20I,IARKS)

a. Organic precipitating agents are prefemed over inorganic precioitant in gravimetricanalysis. Give TWO advantaggs in using organic precipitants.

(2 marlcs)

(4 mar/

;

b. The titrant used in a titration can be prepared from a primary standard or a secondarystandard material. Differentiate the primary standard from the secondary standard. State

three (3) characteristics needed for an ideal primary standard'

" (5 marks)

In an analysis of chloride ion using Mohr method, a25.A0 mL sample containing Cl- is

titrated uring 0.0150 M of a standard solution. An end point is reach after 15.20 mL ofthe titrant has been added.

i. Name the standard solution and indicator used in this analysis.ii. Describe your observation at the end point.iii. The titration should not be performed in a very basic medium (pH > 10) or acidic

medium (pH < 7). ExPlain.

(5 marlcs)

In a titration of a-Jtrong acid-igith ujtto"-!g;e-50.0 mL aliquot of 0.10 Mhydrochloric acid, HCI is titrated with 0.20 M sodium hydroxide, NaOH.

Calculate,h"&tdul$f the HCI solution.

What will the new pH of the solution be after the addition of 15.00 mL of NaOI{?

(5 marks)

d"

l.

1t.

QUESTION 3 (20 MARIdS)

-3 4aa. Chromatographic processes basically involve separation of components fi'om a mixture

and is govemed by thq typ" of int"tu"tiom and properties of the paDescribe briefly the following tecliniques contmonly used in chromatography :

i. adsorptionii. ion-exchangeiii. size exclusion

^_ Q+2+2 marks)

I------1b. Describe thef physicalldiffersnces between an -?p9Llglglar and packed column used incc

(4 marks)

c- A chromatogram of achromaiography column is0.40 mL.min-r.

qgo-grryglgtr mixture onshown in the figure below.

a 25-cm packed liquidThe flow rate was set at

l6

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2

w*,20 30

Time, mi

Find the retention times for A and B.

Determine the retention factors for the two components.

Find the resolution of the fwo peaks. r

Find the Xvefgg,l]gkr of plates for the "olumn. N -

Find the averase plate height (HETP) F{ .: !

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I B.

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(10 marks)

4.tSQUBSTION 4 (20 MARKS)

Spectroscopy is a technique that involves light and matter.

i. Define molar absorptivity ( e ) and transmittance

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i

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A. @i,lu(2 marks)

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j@ii. Draw a schernatic diagram showing the.basic components of a spectrometer and

state the function of each component

of interference in atomic absorption spectroscopy and

atomic absorption instruments

(3 nmrks)

gave ok transmittance of 80.1 in a

? (iii.')The terms Chromophgres and Auxochromes' \--z/ spectrophotometry. Define these two terms.

are

(4 marks)

commonly used in UV-Vis

iv. Name ONE typeovercome it?

-

(2 marlcs)

suggest to

(2 nzarks)

.7\.v. Explain(whyle detection limits of graphite furnacer \ jt

are lowerFompared to flame instrumentation.

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b. A solution containing 6.89 x 10-6 M of analyte ZI cm cell. Determine the.absol!rye and path length needed for a 50% transmittance.

(3 marks)

cThe drug toibutamin e (270 grnol-r) has molar aUso.fuvit y 7A3.0 at 262 nm. One tabletofthedrugwasdissolvedinwaterand.Iftlresolutionhas an absorbance of 0.687 in a I cm cell, how many granls of tolbutarnine are presentin the tablet?

(4 marks)

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