Scheme of Analysis ch 2

Scheme of Analysis ch 2 - Michael Bekhit Chemistry II...

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Michael Bekhit Chemistry II Assignment 2 Scheme February 23, 2007 Section 0745 Solutions needed 15M HONO 2 -to clean Deionized water 6M HAc Sodium cobaltnitrite reagent HBtb pH tester Methyl red tester Thymol Blue tester Methyl Orange AgNO 3 - a few drops 18M HONO 2 – a few drops Ba(NO 3 ) 2 - a few drops Crystal of Fe(OH 2 ) 6 (NH 4 ) 2 (SO 4 ) 2 A few drops of 18M (HO) 2 SO 2 Supplies needed Litmus paper-red and blue Filter paper Cork and wire Vials Matches Possibilities Cations- Na + , K + , NH4 + Anions- Cl - , SO 4 -2 ,HSO 4 - , HO - , NO 3 - Description of unknown Describe phase, color, odor, crystal shape and an indication of whether the sample appears to be a mixture Prepare Solution Approximately one half to two thirds of the unknown should be dissolved in 10- 15mL of deionized water. However a portion of the original should remain!!! Test with solids and water solutions 1) Flame test
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a) clean wire with 15 M HNO 3 and deionized water b) Heat the wire to make sure there is no flame color c) Using a nichrome wire, make a small loop, insert into the flame. If it produces flame color then clean the loop by dipping in 16M HNO 3 . Re- check and repeat cleaning until no flame color is visible, then finally clean with de-ionized water. d) Moisten loop with de-ionized water, touch unknown, and place into flame. i. No color then there is no Na + , K + present ii. If Orange then Na + is present, but its also possible for NH 4 or K + iii. Purple then K + is present possible NH 4 + Test with water solutions Solution Preparation Dissolve a little bit more than ½ to 2/3of the unknown in 10-15ml of de-ionized water. Save remaining unknown. 2) Colbaltinitre tests a) Combine 6 drops of 6M HAc, 2-3 drops of sodium cobaltnitrite reagent, and 10-15 drops of test solution. b) Allow the mixtures to sit until precipitates form c) Transfer a sample of each mixture to filter paper i. If filter paper is clear of color, K + is present ii. If filter paper is dark yellow, NH 4 + is present iii. If filter paper is light yellow, Na
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Scheme of Analysis ch 2 - Michael Bekhit Chemistry II...

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