qualitative tests

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  • inorganic identification tests
    • appearance
      • observe colour and state;state whether crystalline or powder
        • white crystalline solid
          • doesn't contain a transition metal/ion
            • compound grp I/II or ammonium compound
    • solubility in water
      • add a few spatula measures of solid to a test tube of deionised water and shake to mix
        • dissolves to form a colourless solution
          • soluble in water
            • grp i/ii, Al,Zn or ammonium compound
        • dissolves to form a solution (state colour)
          • soluble in water
            • if blue suggests Cu2+ ions present
        • doesn't dissolve in water
          • insoluble
    • flame tests
      • dip a nichrome wire loop into concentrated HCL, touch sample with loop, then hold in blue bunsen flame
        • yellow/orange flame
          • sodium ion
        • crimson flame
          • lithium ion
        • lilac (pink through cobalt blue glass) flame
          • potassium ion
        • brick red flame
          • calcium ion
        • green flame
          • barium ion
        • blue-green/ green-blue flame
          • copper ion
    • testing for halide ions using silver nitrate
      • dissolve a spatula measure of solid sample into  dilute nitric acid
        • and add a few cm3 of silver nitrate solution
          • add dilute /concentrated ammonia solution
            • WHITE PPT which redissolves in both dilute and conc
              • forms a colourless solution
                • chloride ion  present
            • CREAM PPT which doesn't dissolve in dilute ammonia but redissolves in conc
              • to form a colourless solution
                • bromide ion present
            • YELLOW PPT which doesn't redissolve in either dilute or conc
              • iodide ion present
    • testing for sulfate ions using barium chloride
      • dissolve a spatula measure of the solid sample in dilute nitric acid
        • add a few cm3 of barium chloride solution
          • WHITE PPT formed
            • sulfate ions present /SO42-
          • NO PPT formed= NO SULFATE IONS
    • testing for carbonate ions using dilute acid
      • place a few cm3 of dilute acid into a test tube and add a spatula measure of the solid sample
        • effervescence; solid disappears
          • gas evolved can be passed though lime water in another test tube via deliver tube
            • lime water colourless to milky
          • carbonate ions present
        • NO effervescence=NO carbonate ions
    • testing for ammonium ions
      • place a few cm3 of sodium hydroxide into a test tube and add a spatula measure of the solid sample- warm gently
        • test any gas with damp red litmus/UI
          • pungent gas evolved, damp indicator paper turns blue
            • ammonium ion present
            • ammonia gas is alkaline
        • or using a glass rod dipped in conc HCL
          • white smoke
    • test for iodine with starch
      • add few cm3 of starch solution to a sample
        • blue-black colour observed
          • iodine present
        • no blue-black colour observed
          • no iodine present

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