OCR - A-Level - Chemistry - Testing for Ions Flowchart

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• Testing for ions

• Add dilute strong acid

• Bubble the gas released through limewater

• Does it go cloudy?

• Carbonate ion, CO3 ^(2-)

• Yes

• Add dilute hydrochloric acid and barium chloride

• Is a white precipitate formed?

• Sulfate ion,SO4 ^(2-)

• Dissolve in water

• No

• Yes

• Add aqueous silver nitrate

• Is the colour obvious?

• Add dilute aqueous ammonia

• No

• No

• Note the colour

• Is the colour obvious?

• Yes

• Yes

• Add concentrated aqueous ammonia

• Is the colour obvious?

• Yes

• Is there a white precipitate?

• Silver chloride, AgCl

• No

• No

• Is there a cream precipitate?

• Silver bromide, AgBr

• Is there a yellow precipitate?

• Silver iodide, AgI

• Does it dissolve in dilute ammonia?

• Does it dissolve in concentratedammonia?

• Yes

• Yes

• Yes

• Yes

• No

• No

• No

• No

• No

• Add sodium hydroxide solution and heat

• Test the gas released

• Does it turn red litmus paper blue?

• No

• Ammonium ions

• Yes