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CHE3704 ANALYTICAL CHEMISTRY 2021 TUTORIAL LETTER 202
- Institution
- University Of South Africa (Unisa)
This document contains the answers to assignment 2 for CHE
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CHE3704/202/3/2021Tutorial Letter 202/3/2021
Analytical Chemistry III (Theory)
CHE3704
Semesters 1 & 2
Department of Chemistry
IMPORTANT INFORMATION
Please register on myUnisa, activate your myLife e-mail account and
make sure that you have regular access to the myUnisa module
website, CHE3704-2021-S1/S2, as well as your group website
BARCODE
, ASSIGNMENT 02 SOLUTIONS
Question 1 Solutions
(a) Definitions of some terms used in spectroscopy:
(i) Atomization is defined as the process of producing an atomic gas or vapour by applying energy
to the sample (in solution) for its volatilization and decomposition.
(ii) Nebulization is defined as the process I which a liquid is converted into a mist or an aerosol (a
fine spray of droplets) by the flow of gas around the end of a capillary tube and the other end is
immersed in the liquid.
(iii)Aerosol is defined as a suspension of either a solid or a liquid in a gas and it is formed through
nebulization.
(iv) Plasma is defined as a conducting gas that contains a large concentration of ions and/or
electrons.
(v) Dielectric is defined as an electrical insulator that can be polarized by an applied electrical field.
(vi) Interferences are defined as the species that affect the signal on which an analysis is based.
(vii) Modulation is defined as a process of superimposing the analytical signal on a carrier wave,
which may be amplitude or frequency that varies with the analytical signal to convey information
about the signal.
(viii) Radiation buffer is defined as a substance that is added in large excess to both standards and
samples in atomic spectroscopy to prevent the presence of that substance in the sample matrix
from having an appreciate effect on the results.
(ix) Doppler broadening is defined as an increase in the width of the atomic lines caused by the
Doppler effect in which atoms moving toward a detector absorb or emit wavelengths that are
slightly shorter than those absorbed or emitted by atoms moving at right angles to the detector.
(x) Emission is defined as the release of a photon when an analyte (excited and/or ionized analyte)
returns to a lower energy state (a ground state) from a higher energy state (an excited state).
(b) The block diagrams for atomic emission and atomic absorption spectrometers are shown
below.
The atomic emission spectrometer is of a typical inductively coupled plasma atomic emission
spectrometer, while
the atomic absorption spectrometer is of a single-beam atomic absorption spectrometer.
(i) Block diagram of a typical ICP atomic emission spectrometer. (rf denotes radiofrequency.)
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