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Analytical Chemistry (24 hours)

Students should learn Students should be able to a. Detecting the presence of chemical

species

 detecting the presence of calcium, copper, potassium and sodium in substances by the flame test

 application of appropriate tests for detecting the presence of

i. molecules: hydrogen, oxygen, chlorine, carbon dioxide, water, ammonia, sulphur dioxide and hydrogen chloride ii. cations: aluminium,

ammonium, calcium, magnesium, copper(II), iron(II), iron(III) and zinc iii. anions: chloride, bromide,

iodide, carbonate, hypochlorite and sulphite

iv. various functional groups in carbon compounds: C=C,

OH, CHO, >C=O and

COOH

select appropriate tools and apparatus for chemical tests

gather empirical information using chemical tests

record observations accurately and systematically

decide on and carry out an appropriate chemical test to detect the presence of a chemical species

justify the conclusion of the presence of a chemical species either orally or in written form

assess possible risks associated with chemical tests

state the reaction conditions and observations of the tests for the presence of carbonyl compounds using 2,4-dinitrophenylhydrazine and Tollens’

reagent

devise a scheme to separate a mixture of known substances

b. Separation and purification methods

 crystallisation

 distillation / fractional distillation

 liquid-liquid extraction

 paper, column or thin layer chromatography

describe various separation and purification methods

separate and purify substances by the following methods:

i. crystallisation

ii. distillation / fractional distillation iii. liquid-liquid extraction

iv. chromatographic methods

determine the Rf values of substances in a chromatogram

determine the melting point or boiling point of a substance

examine the purity of a substance by measuring its melting or boiling point

justify the choice of an appropriate method used for the separation of substances in a mixture

Students should learn Students should be able to c. Quantitative method of analysis

 volumetric analysis gather data with appropriate instruments and apparatus in quantitative analysis

record observations and data accurately and systematically

be aware of and take necessary steps to minimise possible sources of error

perform calculations on data obtained to draw evidence-based conclusions

present observations, data, results, conclusions and sources of error either orally or in written form

justify the choice of an appropriate quantitative method for the determination of the quantity of a substance

assess possible risks associated with quantitative analysis

d. Instrumental analytical methods

 basic principles and applications of colorimetry

 identification of functional groups of carbon compounds using IR spectroscopy

 basic principles and applications of mass spectrometry, including simple fragmentation pattern

understand the basic principles deployed in the instrumental analytical methods, viz. colorimetry, IR spectroscopy and mass spectrometry

construct a calibration curve by measuring absorbance of standard solutions

determine the concentration of a solution using a calibration curve

identify the following groups from an IR spectrum and a given correlation table: CH, OH, NH, C=C, CC, C=O and CN

identify the following groups from a mass spectrum: R+, RCO+ and C6H5CH2

+

analyse data from primary sources and draw evidence-based conclusions

analyse data from secondary sources, including textual and graphical information, and draw evidence-based conclusions

communicate information, and justify and defend evidence-based conclusions in both written and oral forms

Students should learn Students should be able to e. Contribution of analytical chemistry to

our society

 analysis of food and drugs

 environmental protection

 chemistry aspects of forensic science

 clinical diagnoses

recognise the use of modern instrumentation for analysis in daily life

discuss the role of analytical chemistry in modern ways of living such as gauging levels of

atmospheric pollutants like CO and dioxin, and indoor air pollutants like formaldehyde

describe the role of forensic chemistry in providing legal evidence

discuss the role of analytical chemistry in the diagnosis, treatment and prevention of diseases

Suggested Learning and Teaching Activities

Students are expected to develop the learning outcomes using a variety of learning experiences. Some related examples are:

 devising a scheme to separate a mixture of known substances.

 performing experiments to detect the presence of certain chemical species in a sample.

 designing and performing an investigation to deduce the chemical nature of a sample.

 performing an experiment for the titrimetric analysis of chloride using silver nitrate with chromate indicator (Mohr’s method).

 performing an experiment for the titrimetric analysis of the amount of hypochlorite in a sample of bleach.

 investigating the iron content in some commercial ‘iron tablets’.

 performing an experiment for the iodometric titration of ascorbic acid in a sample of vitamin C tablets or fruit juices.

 performing experiments to detect the presence of functional groups by simple chemical tests.

 performing an experiment to analyse a mixture by paper chromatography, column chromatography or thin layer chromatography.

 performing experiments to separate and identify the major components of the selected over-the-counter analgesics by thin layer chromatography.

 planning and performing an experiment to determine the concentration of an unknown solution using a colorimeter.

 performing experiments to determine the amount of food dye present in soft drinks by using custom-made LED colorimeter.

 analysing data provided in graphical forms like spectra, drawing evidence-based conclusions, and presenting them orally or in written form.

 reviewing laboratory reports and presenting critical comments orally or in written form.

 discussing the importance of integrity in recording and reporting data.

 designing and making a portable alcohol breathalyser and testing its accuracy.

 searching for and presenting information on the principle and application of instrumental analysis such as gas chromatography for blood alcohol content.

 identifying fingerprints by iodine sublimation.

 searching for and presenting information related to the use of chemical methods in forensic science.

 viewing video on the use of modern chemical techniques in chemical analysis.

Values and Attitudes

Students are expected to develop, in particular, the following values and attitudes:

 to be committed to the impartial and objective gathering, analysing and reporting of information.

 to respect the views of others and evidence-based conclusions.

 to appreciate the importance of knowledge and understanding in analytical chemistry and of the practices used to our society.

 to show a continuing interest in and curiosity about the advancement of science.

 to appreciate the importance of following standard methods and chemical analysis, and of validating measurements.

STSE Connections

Students are encouraged to appreciate and comprehend issues which reflect the interconnections of science, technology, society and the environment. Related examples are:

 Separation and purification techniques are used both in the laboratory and in daily life.

The supply of clean water to people in metropolitan districts involves a number of techniques such as filtration, precipitation and distillation. For travellers to rural districts, ‘safe’ drinking water can be made from water obtained from natural sources by adding iodine tincture followed by ascorbic acid.

 Consumers often read reports of food containing carcinogens, heavy metals, pesticides, herbicides, or insecticides. Analytical chemists, with the aid of suitable tools and instruments, can provide information to assist in the understanding of the incidents.

 Chemicals of different natures can cause different threats or hazards to our environment.

Analytical chemistry can provide qualitative and quantitative evidence in such cases.

2.3.3 Investigative Study