Qualitative Analysis

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Qualitative Analysis
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Qualitative WhatQuantitative How much
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Experimental Objective

• Identify the cation and anion present in an
  unknown ionic compound
• Week 1 cation
• Week 2 - anion

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Identify the Cation

• One of seven cations
• Ba2, Ni2, Cu2, Co2, Fe3, Cd2, Mn2
• Identification methods
• Color of cation in solution
• Clear
• colorless
• Reactions of cation in solution
• Seven reaction tests
• Pages 131-133

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Ba 2 N i2 Cu 2 Co 2 Fe 3
Cd 2 Mn 2 unknown
Reactions of cations in solution - Reactants

• Known cation solutions
• Unknown in solution
• Test reagents

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Ba 2 N i2 Cu 2 Co 2 Fe 3
Cd 2 Mn 2 unknown
Reactions of cations in solution Known cation
solutions

• Obtain 1-2 ml in test tubes from stock in buret
• Test tubes in order in test tube rack
• Disposable droppers in each tube
• 2 drops of a solution in each well of a column

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Ba 2 N i2 Cu 2 Co 2 Fe 3
Cd 2 Mn 2 unknown
Reactions of cations in solution Unknown
solution

• Prepare solution of unknown
• Test tube
• Small amount
• Deionized water
• Disposable dropper
• 2 drops of solution in each well of last column

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Ba 2 N i2 Cu 2 Co 2 Fe 3
Cd 2 Mn 2 unknown
Reactions of cations in solution Test Reagents

• Dropper bottles on benchtops
• Do NOT contaminate bottle tips

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Ba 2 N i2 Cu 2 Co 2 Fe 3
Cd 2 Mn 2 unknown
Reactions of cations in solution React,

• One test at a time
• All wells in the row
• Mix with ½ toothpick
• NH3 test last

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Ba 2 N i2 Cu 2 Co 2 Fe 3
Cd 2 Mn 2 unknown
Reactions of cations in solution Observe

• Formation of solid, ?
• Precipitate (color)
• Supernate (color)
• No reaction, NR
• Compare to unreacted solution
• Compare unknown to knowns
• Tips
• Place well plate on white paper
• Carefully lift wellplate to observe from bottom

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Ba 2 N i2 Cu 2 Co 2 Fe 3
Cd 2 Mn 2 unknown
Reactions of cations in solution Record

• Formation of solid ?
• precipitate (color)
• Supernate (color)
• No reaction is a recordable result, NR
• Notes on comparisons
• Identification of cation

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Eliminate (minimize) contamination

• Wash test tubes
• Dish soap and water
• Deionized rinse
• Drying not necessary
• Use deionized water for solution of unknown
• Use dedicated droppers
• Assume bench top is contaminated

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Waste Handling

• All waste in labeled waste containers
• Well plates in provided, marked boxes

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Next Week Qualitative Analysis Anions