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Anion and Cation Test

This document provides information on qualitative chemical analysis, including: 1) Tests for common anions like carbonate, chloride, bromide, and sulfate using silver nitrate and other reagents. 2) Tests for common aqueous cations like aluminum, ammonium, calcium, and copper using sodium hydroxide and ammonia which cause precipitation or color changes. 3) Tests for common gases like ammonia, carbon dioxide, chlorine and oxygen using their reactions with substances like litmus paper or potassium manganate. 4) Flame tests that identify metal ions like lithium, sodium, and copper based on the color they impart to a flame.

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518 views2 pages

Anion and Cation Test

This document provides information on qualitative chemical analysis, including: 1) Tests for common anions like carbonate, chloride, bromide, and sulfate using silver nitrate and other reagents. 2) Tests for common aqueous cations like aluminum, ammonium, calcium, and copper using sodium hydroxide and ammonia which cause precipitation or color changes. 3) Tests for common gases like ammonia, carbon dioxide, chlorine and oxygen using their reactions with substances like litmus paper or potassium manganate. 4) Flame tests that identify metal ions like lithium, sodium, and copper based on the color they impart to a flame.

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Cambridge IGCSE Chemistry 0620 syllabus for 2020 and 2021.

  Details of the assessment

Notes for use in qualitative analysis

Tests for anions


anion test test result
carbonate (CO32–) add dilute acid effervescence, carbon dioxide produced
chloride (Cl –) acidify with dilute nitric acid, then add white ppt.
[in solution] aqueous silver nitrate
bromide (Br–) acidify with dilute nitric acid, then add cream ppt.
[in solution] aqueous silver nitrate
iodide (I–) acidify with dilute nitric acid, then add yellow ppt.
[in solution] aqueous silver nitrate
nitrate (NO3–) add aqueous sodium hydroxide, then ammonia produced
[in solution] aluminium foil; warm carefully
sulfate (SO42–) acidify, then add aqueous barium nitrate white ppt.
[in solution]
sulfite (SO32–) add dilute hydrochloric acid, warm gently sulfur dioxide produced will turn acidified
and test for the presence of sulfur dioxide aqueous potassium manganate(VII) from
purple to colourless

Back to contents page www.cambridgeinternational.org/igcse 31


Cambridge IGCSE Chemistry 0620 syllabus for 2020 and 2021.  Details of the assessment

Tests for aqueous cations


cation effect of aqueous sodium hydroxide effect of aqueous ammonia
aluminium (Al 3+) white ppt., soluble in excess, giving a white ppt., insoluble in excess
colourless solution
ammonium (NH4+) ammonia produced on warming –
calcium (Ca2+) white ppt., insoluble in excess no ppt. or very slight white ppt.
chromium(III) (Cr3+) green ppt., soluble in excess grey-green ppt., insoluble in excess
copper(II) (Cu2+) light blue ppt., insoluble in excess light blue ppt., soluble in excess, giving a
dark blue solution
iron(II) (Fe2+) green ppt., insoluble in excess green ppt., insoluble in excess
iron(III) (Fe3+) red-brown ppt., insoluble in excess red-brown ppt., insoluble in excess
zinc (Zn2+) white ppt., soluble in excess, giving a white ppt., soluble in excess, giving a
colourless solution colourless solution

Tests for gases


gas test and test result
ammonia (NH3) turns damp red litmus paper blue
carbon dioxide (CO2) turns limewater milky
 
chlorine (Cl 2) bleaches damp litmus paper
hydrogen (H2) ‘pops’ with a lighted splint
oxygen (O2) relights a glowing splint
sulfur dioxide (SO2) turns acidified aqueous potassium manganate(VII) from purple to colourless

Flame tests for metal ions


metal ion flame colour
lithium (Li+) red
sodium (Na+) yellow
potassium (K+) lilac
copper(II) (Cu2+) blue-green

32 www.cambridgeinternational.org/igcse Back to contents page

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