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QualitativeAnalysis-
Anions only
Question | Answer |
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What are the anions that are to be learnt? | Carbonate,CO3 2-, sulphate, SO4 2-, sulphite, SO3 2-, Chloride, Cl -, Bromide, Br -, Iodide, I - and nitrate, NO3 -. |
How do you identify carbonate, CO3 2-, nitrate, NO3 - and sulphite, SO3 2- anions? | These anions are identified by heating a sample of them. |
How do you identify the presence of CO3 2-? | When heated carbon dioxide emerges and forms a white precipitate in the lime water. |
How do you identify the presence of NO3-? | When heated a brown gas evolved with an irritating smell and a glowing splint relit. |
How do you identify the presence of SO3 2-? | When heated sulphur dioxide evolves and gives off a choking smell which turned orange acidified potassium dichromate green. |
Using dilute nitric/hydrochloric acid how do we identify carbonate, CO3 2-? | Effervescence occurs and a white precipitate is formed in the lime water. |
Using dilute nitric/hydrochloric acid how do we identify sulphite, SO3 2-? | Effervescence accurs and a gas with a choking smell emerges on heating turning orange acidified potassium dichromate green. |
Using concentrated sulphuric acid how do we identify carbonate, CO3 2-? | When the concentrated sulphuric acid is added, carbon dioxide emerges and it forms a white precipitate in lime water. |
Using concentrated sulphuric acid how do we identify sulphite, SO3 2-? | When the concentrated sulphuric acid is added sulphur dioxide emerges which turns orange potassium dichromate solution green. |
Using concentrated sulphuric acid how do we identify Chloride, Cl-? | When the concentrated sulphuric acid is added hydrogen chloride emerges and forms white fumes with ammonia gas. |
Using concentrated sulphuric acid how do we identify Bromide, Br-? | When concentrated sulphuric acid is added a brown bromine vapour emerges. |
Using concentrated sulphuric acid how do we identify Iodide, I-? | When concentrated sulphuric acid is added a black solid iodine is produced which sublimes to a purple vapour if heated. |
What test can we carry out to identify the halide ions? And what are the halide ions? | We identify the halide ions by using silver nitrate solution followed by aqueous ammonia. The halide ions are Cloride Cl-, Bromine Br- and Iodide I-. |
Using silver nitrate followed by aqueous ammonia how do we identify Chloride, Cl-? | When silver nitrate followed by aqueous ammonia is added a white precipitate forms which turns violet when exposed to sunlight and its also soluble in ammonia solution. |
Using silver nitrate followed by aqueous ammonia how do we identify Bromide, Br-? | When silver nitrate followed by aqueous ammonia solution is added a cream precipitate forms which turns yellow green when exposed to sunlight and it is slightly soluble in ammonia solution. |
Using silver nitrate followed by aqueous ammonia how do we identify Iodide, I-? | When silver nitrate followed by aqueous ammonia solution is added a pale yellow precipitate forms and is insoluble in ammonia solution. |
Using barium nitrate or chloride followed by dilute acid (HNO3 or HCL) how do we identify Sulphate SO4 2-? | When barium nitrate followed by dilute acid is added a white insoluble precipitate forms. |
Using barium nitrate or chloride followed by dilute acid (HNO3 or HCL) how do we identify carbonate CO3 2-? | When barium nitrate followed by dilute acid is added a white soluble precipitate forms and carbon dioxide emerges. |
Using barium nitrate or chloride followed by dilute acid (HNO3 or HCL) how do we identify Sulphite SO3 2-? | When barium nitrate followed by dilute acid is added a white soluble precipitate forms and sulphur dioxide emerges. |
When concentrated sulphuric acid and copper turnings are added to a solid and warmed gently what do we observe? | A blue solution forms and nitrogen dioxide emerges. |
'Make a solution of the solid then add satured iron (II) sulphate and mix. Add concentrated sulphuric acid down the side of the test tube.'What is this test named and what do we observe? | This test is called the brown ring test and in this test the sulphuric acid sinks and forms a brown ring between the two layers. |