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 INORGANIC Qualitative TESTS Anions and Alkalis CHEMICAL TEST FOR TEST METHOD OBSERVATIONS TEST CHEMISTRY Chemical test for  Carbonate  ion CO 3 2–  or hydrogencarbonate HCO 3 –  ion Acid is added to the solid carbonate in a test tube. You could also collect a sample of gas from a heated carbonate, i.e. the solid is where the liquid is in the left hand test tube. Methods of gas preparation are described in more detail on another page. (i)  Add  any dilute strong acid  to the suspected solid carbonate – if  colourless gas  given off, test with  limewater . (ii)  Effect of fairly strong heating and testing for any carbon dioxide given off. Test (ii) will  distinguish  sodium hydrogencarbonate ( NaHCO 3  readily decomposes – 'baking powder') from anhydrous sodium carbonate ( Na 2 CO 3 , thermally very stable). (i)  Fizzing –  colourless gas which  turns limewater milky – cloudy fine  white precipitate  (see above CO 2 ). (ii)  There might be colour changes in the solid, b

 INORGANIC Qualitative TESTS for gases and non–metallic elements CHEMICAL TEST FOR ... TEST METHOD OBSERVATIONS TEST CHEMISTRY and comments hydrogen  gas H 2 Apply a  lit splint  or spill. A squeaky pop!  (might see condensation on test tube) 2 H 2 (g)  + O 2(g)  ==> 2H 2 O (l)  +  energy! Chemical test for  carbon dioxide  gas CO 2 Bubble the gas into  limewater  (aqueous calcium hydroxide solution). It turns cloudy  – fine milky  white precipitate of calcium carbonate. BEWARE – the calcium carbonate precipitate dissolves in excess carbon dioxide, so don't overdo the test! Ca(OH) 2(aq)  +  CO 2 (g)  ==>  CaCO 3(s)   + H 2 O (l) If excess carbon dioxide bubbled through you form a clear colourless solution of calcium hydrogencarbonate. CaCO 3(s)  + H 2 O (l)  + CO 2(aq)  ==>  Ca(HCO 3 ) 2(aq) so beware of overdoing this test! Chemical test for  oxygen  gas O 2 Apply a  glowing splint or spill. It  re–ignites to a flame . C (in wood)  +  O 2 (g)   ==> CO 2(g) Th

Of what use is chemical analysis and chemical testing? Well, rather a lot, as it happens! The production of many products we use in our society involved some kind of chemical analysis at some stage or other. It might analysing mineral ores for their metal content or testing the final purity of some drug/medicine from the pharmaceutical industry. For chemical analysis analysts have developed a wide range of qualitative tests to detect specific chemicals which may be molecules or ions. Chemical tests are based on reactions that produce a gas with distinctive properties, or a colour change produced by adding a reagent or the production of an insoluble solid that appears as a precipitate. Modern instrumental methods provide a fast, sensitive and accurate means of analysing chemicals, and are particularly useful when the amount of chemical being analysed is small. Forensic scientists and drug control scientists rely heavily on such instrumental methods in their work. Environmental

What is Qualitative Analysis? Qualitative analysis is a method of Analytical chemistry that deals with the determination of elemental composition of inorganic salts. It is mainly concerned with the detection of ions in an aqueous solution of the salt. The common procedure for testing any unknown sample is to make its solution and test this solution with various reagents for the ions present in it. Testing with various reagents gives characteristic reaction of certain ions, which may be a colour change, a solid formation or any other visible changes. There are separate procedures for detecting cations and anions, called the Cation Analysis and Anion Analysis. Let us discuss about the Qualitative Analysis of Cations. Qualitative Analysis of Cations Preliminary Tests Some preliminary tests needs to be done before doing the analysis of cations. (a) Physical Appearance: Colour and Smell The physical examination of the unknown salt involves the study of colour,