Qualitative Analysis Flashcards
Aluminium when NaOH is added?
White precipitate of aluminium hydroxide is formed which dissolves in excess to form a colourless solution
Aluminium with ammonia
White precipitate is formed and insoluble in excess
Zinc with a few drops of NaOH
White precipitate of zinc hydroxide is formed and dissolves in excess to form a colourless solution
Lead with NaOH
White precipitate of lead hydroxide is formed which dissolves in excess to form a colourless solution
Calcium with NaOH
White precipitate of calcium hydroxide is formed which is insoluble in excess
Copper (II) with NaOH
Light blue precipitate of Copper (II) hydroxide formed and is insoluble in excess
Iron (II) with NaOH
Green precipitate of Iron (II) hydroxide formed which is insoluble in excess. Turns red-brown when left to stand
Ammonia with NaOH
No precipitate, ammonia gas is given off upon heating, turns red litmus paper blue. No observable change in excess.
Zinc with ammonia
White precipitate of zinc hydroxide formed and dissolves in excess to form colourless solution
Lead with ammonia
White precipitate of Lead hydroxide formed and is insoluble in excess
Aluminium with ammonia
White precipitate of aluminium hydroxide formed and is insoluble in excess
Calcium with ammonia
No precipitate formed and no observable change in excess
Copper (II) with ammonia
Light blue precipitate of copper hydroxide formed and dissolves in excess to form a dark blue solution
Iron (II) with ammonia
Green precipitate of Iron (II) hydroxide is formed and is insoluble in excess but turns red brown when left to stand
Iron (III) with ammonia
Reddish-brown precipitate of iron (III) hydroxide is formed and is insoluble in excess
Test for carbonate ion
Add dilute acid and bubble the gas into limewater. Carbonate + acid = Salt + water + CO2; limewater will turn chalky as gas will react with calcium carbonate to form a precipitate. Effervescence is given off and CO2 is produced
Test for Nitrate Ion
Add NaOH and a piece of aluminium. Warm the mixture and use a damp litmus paper to test for the gas produced. Effervescence is observed and the red litmus paper turns blue if ammonia is produced
Test for sulfate ion
Add dilute nitric acid then add aq barium nitrate. White precipitate of barium sulfate will be formed
Test for Chloride ion
Add dilute nitric acid, then add aq silver nitrate. White precipitate of silver chloride will be formed
Test for iodide ion
Add dilute nitric acid, then add aq silver nitrate. Yellow precipitate of silver iodide will be formed
Why add dilute nitric acid
Dissolve impurities (usually carbonate) or to dissolve solid salt
Why add aq barium/ silver nitrate
To form insoluble salt
Test for Hydrogen
Place a burning/ lighted splint at the mouth of the test tube. Presence of hydrogen will make it extinguish with a pop sound
Test for oxygen
Insert a glowing splint into the test tube. Presence of oxygen will make it rekindle
Test for CO2
Bubble the gas through limewater. Presence of CO2 will cause a white precipitate to form. Precipitate will dissolve upon further bubbling
Test for chlorine
It is a yellow-green gas with a pungent smell. But a damp blue litmus paper at the mouth of the test tube and it will turn red then bleached in the presence of chlorine
Test for sulfur dioxide
A colourless pungent gas. Place a piece of filter paper soaked in acidified potassium manganate (VII) (KMNO4) at the mouth of the test tube. It will turn from purple to colourless in the presence of sulfur dioxide
Test for ammonia gas
Colourless gas with a pungent smell. Place a piece of damp red litmus paper at the mouth of the test tube. It will turn blue in the presence of ammonia gas
Test for water
1) Heat the salt. A colourless liquid in the form of condensation will appear at the mouth of the test tube in the presence of a hydrate salt
2) Test with anhydrous cobalt (II) chloride paper. It will turn from blue to pink in the presence of water
3) Test with anhydrous copper sulfate (s). It will turn from white to blue in the presence of water.
