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4                           Analytical Chemistry








                                           Analytical Chemistry and Chemical Analysis
                   CONTENTS
                                           The branch of chemistry that deals with the analysis of chemical substances
          ͻ   ŶĂůLJƟĐĂů ĐŚĞŵŝƐƚƌLJ ĂŶĚ ĐŚĞŵŝĐĂů   is called analytical chemistry.
            ĂŶĂůLJƐŝƐ
          ͻ   ŽůŽƵƌ ŽĨ ƚŚĞ ƐĂůƚƐ ĂŶĚ ƚŚĞŝƌ   What is meant by chemical analysis
            ƐŽůƵƟŽŶƐ
          ͻ   ĐƟŽŶ ŽĨ ƐŽĚŝƵŵ ŚLJĚƌŽdžŝĚĞ ƐŽůƵƟŽŶ   The  chemical analysis  KPXQNXGU  KFGPVKſECVKQP  CPF  FGVGTOKPCVKQP  QH  VJG
            ŽŶ ĐĞƌƚĂŝŶ ŵĞƚĂůůŝĐ ƐĂůƚ ƐŽůƵƟŽŶƐ  composition of the chemical components present in any given substance.
          ͻ   ĐƟŽŶ ŽĨ ĂŵŵŽŶŝƵŵ ŚLJĚƌŽdžŝĚĞ ŽŶ
            ĐĞƌƚĂŝŶ ŵĞƚĂůůŝĐ ƐĂůƚ ƐŽůƵƟŽŶƐ      Chemical analysis is of two types –  qualitative analysis and
          ͻ   ĐƟŽŶ ŽĨ ĂŵŵŽŶŝƵŵ ŚLJĚƌŽdžŝĚĞ ŽŶ   quantitative analysis.
            ĐŽƉƉĞƌ ƐƵůƉŚĂƚĞ ƐŽůƵƟŽŶ
          ͻ   ĐƟŽŶ ŽĨ ƐŽĚŝƵŵ ŚLJĚƌŽdžŝĚĞ ŽŶ    ƒ  Qualitative analysis:  +V  OCKPN[  KPXQNXGU  KFGPVKſECVKQP  QH  VJG
            ĂŵŵŽŶŝƵŵ ƐĂůƚƐ                      constituents of a substance or a mixture of substances.
          ͻ   ĐƟŽŶ ŽĨ ĂůŬĂůŝƐ ŽŶ ĐĞƌƚĂŝŶ ŵĞƚĂůƐ  ƒ  Quantitative analysis: It involves accurate determination of the
          ͻ   ĐƟŽŶ ŽĨ ĂĐŝĚƐͬĂůŬĂůŝƐ ŽŶ ŵĞƚĂů    amounts of various constituents present in any sample.
            ŽdžŝĚĞƐ
                                           The qualitative analysis of any sample involves the following steps:
                                             ƒ  Observation of the physical characteristics, such as solid structure,
                                                colour, density, smell, and solubility.

                                             ƒ  Chemical tests: These are of two types
                                                Dry tests and Wet tests
                                                   Š Dry tests are conducted on dry samples, and include the following
                                                   observations:
                                                      y Effect of heat
                                                      y Colour and smell of the gas/vapour evolved

                                                   Š Wet tests are conducted on the solution of the given salt or salt
                                                   OKZVWTG  6JG YGV VGUVU KPENWFG VJG WUG QH EGTVCKP URGEKſE TGCIGPVU
                                                   on the solution of the given sample.
                                                During wet tests, observations are made for any change in colour,
                                           formation of any precipitate, colour of the precipitate, etc.

                                           Colour of the Salts and Their Solutions

                                           %QNQWT QH VJG IKXGP UCNV QT KVU UQNWVKQP JGNR KP KVU KFGPVKſECVKQP
                                             ƒ  The salts of representative elements (or normal elements), i.e.,
                                                elements of groups 1, 2, (IA, IIA) and 13 to 17 (or groups IIIA to VIIA)
                                                are colourless (except those having oxoanions of transition metals).
                                             ƒ  The salts of transition elements, i.e., salts of elements belonging to
                                                groups 3 to 12 (or groups IB, IIB, IIIB, IVB, VB, VIB, VIIB and VIII) are
                                                generally coloured.
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