Qualitative Analysis

Qualitative Analysis - Qualitative Analysis Page 139 156...

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Qualitative Analysis Page 139 – 156 Pre-lab, pages 143-144, AND 153-154 Post Lab, page 156, all questions
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Introduction to Qualitative Analysis • Qualitative analysis is used to separate and detect cations and anions in a sample substance. • Qualitative analysis is the procedure by which one can determine the nature, but not the amount of species in a mixture.
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Experimental Aims • To observe the chemical properties of: Na + , K + , NH 4 + , Cu 2+ and Bi 3+ • To perform a series of tests that isolate each of these ions.
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Lab Techniques • Ensure all glassware is clean, but it does not need to be dry. • Use distilled water at all times • Label test tubes to avoid confusion • Mix solutions my flicking the test tube • Estimate volumes by assuming 20 drops by pipette 1ml
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Experimental Procedure • You will be provided with 2 test-tubes. • One will contain all of the cations to be detected. This is your reference solution • The other test-tube will contain a number of unknown cations that you will need to identify by experimental observations.
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• Make careful notes of your observations. • Look closely for gases, and note colors of solutions and precipitates. • Part E will be omitted, no other ions other than those listed will be present. • Recap on your solubility rules
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Solubility Guidelines 1. All nitrates are soluble. 2. Practically all sodium, potassium, and ammonium salts are soluble. 3. All chlorides, bromides, and iodides are soluble except those of silver, mercury(I), and lead(II). 4. All sulfates are soluble except those of strontium, barium, and lead(II), which are insoluble, and those of calcium and silver which are moderately soluble. 5. All carbonates, sulfites, and phosphates are insoluble except those of sodium, potassium, and ammonium.
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Types of reactions • Precipitation • Complex ion formation • Redox reactions • Acid-base reactions
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Some means of identifying ions by qualitative analysis are : • Color changes, • Evolution of gas • Change in pH (acidity or basicity) • or ability to redissolve a precipitate by addition of a complexing ligand.
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• If a gas is given off, note the color and odor of the gas. • The nitrate, carbonate, and sulfite ions may decompose, as illustrated by the reactions: •2P b (NO 3 ) 2 (s) + heat --> 2 PbO(s) + O 2 (g) + 4 NO 2 (g, brown) •C aCO 3 (s) + heat --> CaO(s) + CO 2 (g, colorless, odorless) •C a SO 3 (s) + heat --> CaO(s) + SO 2 (g, colorless, pungent) • Some bromides and iodides decompose to give
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• Group I: Ag + , Hg 2 2+ , Pb 2+ Precipitated in 1 M HCl • Group II:
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This note was uploaded on 01/23/2012 for the course CHEM 11 taught by Professor Staff during the Fall '08 term at Concordia AB.

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Qualitative Analysis - Qualitative Analysis Page 139 156...

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