this might have some brown fumes coming from Bromine. If the bromide ion is reacted with a concentrated acid such concentrated sulfuric acid white fumes would be seen, which would be HBr. If the chloride ion is reacted with a concentrated acid such concentrated sulfuric acid white fumes would be seen, which would be HClīr –: Reacting the anion with AgNO 3 would form a pale yellow ppt. S 2-: By reacting the anion with an acid a pungent gas is formed.Ĭl –: Reacting the anion with AgNO 3 would form a white ppt. The gas produced when the anion is reacted with an acid turns blue litmus red. On addition of acid the white precipitate formed disappears. SO 3 2-: The addition of Barium Chloride would form Barium Sulfite which is insoluble. On addition of acid the white precipitate formed does not dissolve. SO 4 2-: The addition of Barium Chloride would form Barium Sulfate which is insoluble. This gas is CO 2 and the reaction is as following: An example is:Īlthough it is important to know that these complexes exist it is a chemistry of its own and students are not expected to know how these complexes form.ĬO 3 2-: With the addition of an acid a colourless and odourless gas which turns limewater milky is created. When the ppt dissolves in excess base a complex would be formed, which would have a charge and therefore it would dissolve in an aqueous solution. M + (aq) + OH – (aq) → MOH (s) for the formation of precipitates The precipitate is the hydroxide of the cation being analysed. It must be noted that it is the precipitate that is the most important, and not the colour of the solution even though the solution takes it colour from the ppt. It is of utter importance to note that it is the ion that produces the coloured flame and not the element.Ī white ppt formed insoluble in excess NaOHĪ blue ppt which dissolves into a blue solution in excess NaOHĪ blue ppt which turns into a deep blue solution in excess ammonium hydroxideĪ white ppt insoluble in excess ammonium hydroxideĪ white ppt soluble in excess ammonium hydroxide There are three sets of tests: flame tests, tests with bases such as NaOH and NH 4OH and tests for anions. These can be used to identify the elements found in a specific compounds. In this case, we show that addition of hydroxide ion to lead(II) ion initially gives a white precipitate of lead(II) hydroxide.Īddition of excess hydroxide ion results in the formation of the colorless soluble tetrahydroxolead(II) complex ion.Ī characteristic test for lead(II) ion is the production of bright yellow lead(II) iodide:Īddition of excess iodide ion results in the formation of the colorless soluble tetraiodoplumbate(II) complex ion.In order to analyse cations and anions a series of tests would have to be performed. Reaction of lead(II) ion with hydroxide ion The production of the gas can be illustrated by damp blue litmus paper turning red. The process continues until almost all of the hydrogen carbonate ion has been consumed.Īddition of any strong acid to a carbonate or hydrogen carbonate will give a release of carbon dioxide gas. Thus addition of calcium ion consumes the carbonate ion and the equilibrium shifts right to replenish the carbonate ion. HCO3-(aq) + HCO3-(aq) ? CO32-(aq) + H2O(l) + CO2(aq)Ĭalcium ion (small, high charge) forms insoluble calcium carbonate (high lattice energy as carbonate is high charge also). The hydrogen carbonate ion is in equilibrium with the carbonate ion in a disproportionation reaction: The indicator changes colour to indicate an acid.ĭisproportionation of the hydrogen carbonate ion Weller, Overton, Rourke & Armstrong: Inorganic Chemistry 6e Chapter 14: Videos of chemical reactionsĪ lump of solid carbon dioxide is placed in water containing a few drops of universal indicator.
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