Difference between revisions of "Qualitative tests for metals"
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| − | A metal test is a test to determine the metal ions within a solution or in an alloy. | + | A '''qualitative metal test''' is a test to determine the [[metal]] ions within a solution or in an [[alloy]]. |
== Methods == | == Methods == | ||
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== Tests == | == Tests == | ||
The tests below show methods for the identification of metal cations within solutions. Lists of which metals react in which way may be helpful if added. | The tests below show methods for the identification of metal cations within solutions. Lists of which metals react in which way may be helpful if added. | ||
| − | * ''Sulfate test'': the sulfate test uses a soluble sulfate (like [[sodium sulfate]]), which is added to a solution containing a metal ion. Certain ions will precipitate readily (like [[barium sulfate]] or [[silver sulfate]]), while others like [[calcium sulfate]] may take longer to precipitate. Most transition metals will not precipitate in this test. | + | * ''Sulfate test'': the sulfate test uses a soluble sulfate (like [[sodium sulfate]]), which is added to a solution containing a metal ion. Certain ions will precipitate readily (like [[barium sulfate]], lead sulfate or [[silver sulfate]]), while others like [[calcium sulfate]] may take longer to precipitate. Most transition metals will not precipitate in this test. |
* ''Ferrocyanide tests'': Many tests involve the use of [[Potassium ferrocyanide|potassium hexacyanoferrate(II)]] and [[Potassium ferricyanide|potassium hexacyanoferrate(III)]], otherwise known as the ferro- and ferricyanide anions. These salts precipitate various transition metals as varied, brightly colored salts. They are also a good indicator of the presence of iron ions, turning a solution deep blue. | * ''Ferrocyanide tests'': Many tests involve the use of [[Potassium ferrocyanide|potassium hexacyanoferrate(II)]] and [[Potassium ferricyanide|potassium hexacyanoferrate(III)]], otherwise known as the ferro- and ferricyanide anions. These salts precipitate various transition metals as varied, brightly colored salts. They are also a good indicator of the presence of iron ions, turning a solution deep blue. | ||
| + | * ''Chlorate/Perchlorate test'': Addition of a conc. solution of [[sodium chlorate]]/[[sodium perchlorate|perchlorate]] to a sample will precipitate any potassium ions present in the sample, due to the low solubility of potassium chlorate/perchlorate. | ||
== References == | == References == | ||
<references/> | <references/> | ||
| + | ===Relevant Sciencemadness threads=== | ||
| − | [[Category: | + | [[Category:Analytical techniques]] |
Latest revision as of 21:22, 4 May 2020
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A qualitative metal test is a test to determine the metal ions within a solution or in an alloy.
Methods
Solution tests usually involve color changes or precipitates to categorize what metals are present within a solution. Thus, they are often limited by concentration, and the solubility of a precipitate within a solvent. Since the metals to be tested are in solution, their anions shouldn't matter within a test. In contrast, the tests are usually based upon the fact that certain metals form insoluble salts with certain anions (like sulfates, or chlorides).
Tests
The tests below show methods for the identification of metal cations within solutions. Lists of which metals react in which way may be helpful if added.
- Sulfate test: the sulfate test uses a soluble sulfate (like sodium sulfate), which is added to a solution containing a metal ion. Certain ions will precipitate readily (like barium sulfate, lead sulfate or silver sulfate), while others like calcium sulfate may take longer to precipitate. Most transition metals will not precipitate in this test.
- Ferrocyanide tests: Many tests involve the use of potassium hexacyanoferrate(II) and potassium hexacyanoferrate(III), otherwise known as the ferro- and ferricyanide anions. These salts precipitate various transition metals as varied, brightly colored salts. They are also a good indicator of the presence of iron ions, turning a solution deep blue.
- Chlorate/Perchlorate test: Addition of a conc. solution of sodium chlorate/perchlorate to a sample will precipitate any potassium ions present in the sample, due to the low solubility of potassium chlorate/perchlorate.
