Chemistry Tests

Pregunta	Respuesta
TESTS FOR GASES	...
Test for Ammonia	- Use damp red litmus paper (or universal indicator) --> goes blue - Place hydrochloric acid close by --> White smoke of aluminium chloride (irritant) forms.
Test for Carbon Dioxide	- Use lime water --> a white precipitate of of calcium carbonate forms which, in time, goes colourless as calcium hydrogen carbonate forms.
Test for Chlorine	- Damp blue litmus paper goes red on formation of chloric (I) acid. This then bleaches the paper.
Test for Hydrogen	- Add a lighted splint --> if the hydrogen is mixed with air there is a 'pop' but if the gas is pure, it catches fire, ad there is no 'pop'.
Test for Hydrogen Chloride	- Damp blue litmus paper (or universal indicator) --> goes red. - Place concentrated ammonia solution close by --> white smoke of ammonium chloride forms.
Test for Nitrogen Dioxide	- Observe colour. Nitrogen dioxide is the only BROWN GAS.
Test for Oxygen	- Add a glowing splint --> This relights the glowing splint, sometimes with a 'pop'.
TESTS FOR ORGANIC FUNCTIONAL GROUPS	...
Test for Primary and Secondary alcohols	Potassium dichromate (VI) test - To 5 drops of the alcohol add 10 drops of 1M sulfuric acid and 4 drops of 0.1M potassium dichromate (VI) solution. Place the solution in boiling hot water from a kettle COLOUR CHANGE: Orange --> Green
Test for Aldehydes and Ketones	TOLLENS REAGENT - On warming Tollen's reagent with an aldehyde --> a silver mirror forms FEHLING'S SOLUTION - Add 5 drops of the aldehyde or ketone to 2cm3 of Fehling's solution. Aldehyde: Blue solution --> Red precipitate (Neither show a change with Ketones)
Test for Carboxylic acids	- Add 2M ammonia solution to 0.1M iron (III) chloride solution until a precipitate just appears. Now add more of the original iron (III) chloride in drops with stirring until the precipitate just dissolves. - Add this to the liquid under test and look for a RED SOLUTION.
Test for Phenol	- To the phenol add neutral iron (III) chloride solution COLOUR CHANGE: brown --> purple
TESTS FOR POSITIVE IONS	...
Flame Tests	> Barium ions --> Greenish flame > Calcium ions --> Brick red flame > Copper (II) ions --> Bluish flame > Lead (II) ions --> White flame > Lithium --> Crimson red flame > Potassium ions --> Lilac flame > Rubidium ions --> Blue flame > Strontium ions --> Crimson flame > Sodium ions --> Persistent yellow flame
Add Sodium hydroxide solution	> Aluminium ions --> White precipitate which dissolves in excess alkali > Ammonium ions --> No precipitate, but odour of ammonia > Barium ions --> White precipitate >Calcium ions --> White precipitate > Copper (II) ions --> Blue precipitate > Iron (II) ions --> Green precipitate > Iron (III) ions --> Brown precitate > Magnesium ions --> White precipitate > Potassium ions --> No precipitate > Sodium ions --> No precipitate
Test for Ammonium ions	- Warm 0.4M sodium hydroxide solution with the test solution --> Ammonia gas will be given off.
Test for Copper (II) ions	- A blue precipitate forms when ammonia solution which dissolves n excess ammonia to give a deep blue solution.
Test for Lead (II) ions	- Forms a bright yellow precipitate when added to 0.1M solution of potassium iodide.
TESTS FOR NEGATIVE IONS	...
Test for Carbonate ions	- Add hydrochloric acid --> produces lots of fizzing (Carbon dioxide identifiable with lime water).
Test for Bromide ions	- Forms a CREAM precipitate with silver nitrate solution which dissolves after the addition of CONC. Ammonia.
Test for Chloride ions	- Forms a WHITE precipitate with silver nitrate solution which dissolves after the addition of 2M Ammonia solution.
Test for iodide ions	- Forms a YELLOW precipitate with silver nitrate solution which is insoluble after the addition of 2M Ammonia solution.
Tests for Nitrate (V) ions	- Brown ring test --> Dissolve the Nitrate (V) in about 1ml of water and add 0.5g of iron (II) sulfate(VI)-7-water. Hold the test tube at an angle and carefully pour about 1ml of conc. sulfuric(VI) acid down te side of the test tube so it forms a layer at the bottom. A brown ring indicates nitrate(V) ions present. - Devada's alloy --> Add 2ml of nitrate (v) to 5ml of 1M sodium hydroxide solution. Add a little Devada's alloy and warm. Test for ammonia gas.
Test for Sulfate (VI) ions	- Forms a white precipitate with barium chloride (deionised water and dissolved oxygen.)

Siguiente

Descripción

Resumen del Recurso

Similar

	Creado por Emily Hargreaves hace más de 7 años