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Published byGloria Goodman Modified over 9 years ago
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Warm-Up: Net Ionic Equation Write a chemical, total ionic, and net ionic equation for the reaction of zinc (II) chloride with potassium carbonate.
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Chemical Analysis LG: I can develop a procedure to test for the presence of ions
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Qualitative analysis – the identification of the specific substances present Quantitative analysis – the measurement of the quantity of a substance present
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Qualitative Analysis Many substances can be identified by their unique physical or chemical properties: – Reactions with other substances to produce a new colour and/or precipitate Example: Phenolphthalein turns pink in basic solutions (reacts with hydroxide ions) – For cations that are usually colourless in solution and highly soluble, a flame test may be used (only works when a single cation is present) Example: Copper = Green, Strontium = Red
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Using Solubility to Identify Ions Ions in solution can be identified by the precipitates they form. This can be done by choosing a test solution that contain ions that will form precipitates with the ‘target’ ions for which we are testing. – Example: A solution of potassium iodide could be used to detect the presence of lead ion
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Try It! A) Use your solubility table to identify a solution that could be used to check for the presence of barium. B) What if you wanted to check for barium and lead? – What solutions could you use? – In what order would you do the tests? Why?
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Sequential Qualitative Chemical Analysis 1) Use the solubility table to identify a soluble ionic compound that can be used to test for the target ion 2) Determine the order in which reactions must occur if the presence of multiple ions are being tested (filter between tests to remove precipitate) 3) Construct a flow chart to keep track of results 4) Recognize that no precipitate means the target ions is not present in solution
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Example A solution is thought to contain calcium and mercury. Design a sequential qualitative analysis to determine whether the solution contains either or both of these ions
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Homework Pg. 441 # 1, 3, 6 (see table 1), 7, 8, 11
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