In the Lab

Question 1

Flame Tests

Answer 1

LIthium: Red
Sodium: Yellow
Potassium: Lilac
Calcium: Orange-red
Barium: Light green
Copper(II): Blue- green

Question 2

Test for Gases

Answer 2

Ammonia turns damp litmus paper blue
Carbon Dioxide turns lime water milky white
Chlorine bleaches damp litmus paper
Hydrogen pops with a lighted splint
Oxygen relights with a glowing splint
Sulphur dioxide turns acidified potassium manganate(VII) from purple to colourless

Question 3

Test for Anions(Hallides and carbonate):

Answer 3

Carbonate: Add a dilute acid and then test for carbon dioxide by bubbling through lime water. Effervescence will be seen and carbon dioxide will be produced.

Chloride: Acidify with dilute nitric acid and add aqueous silver nitrate. White precipitate is produced.

Bromide: Acidify with dilute nitric acid and add aqueous silver nitrate. Cream precipitate will be produced.

Iodide: Acidify with dilute nitric acid and add aqueous silver nitrate. Yellow precipitate will be formed.

Question 4

Test for Anoins (NItrate, Sulphate and Sulphite):

Answer 4

Nitrate: Add aqueous sodium hydroxide and then aluminium foil. Warm carefully. Ammonia will be produced.

Sulphate: Acidify with dilute nitric acid and add aqueous barium nitrate. White precipitate will be formed.

Sulphite: Add a small volume of acidified aqueous potassium manganate(VII). The acidified aqueous potassium manganate(VII) changes from purple to colourless.

Question 5

Test for Cations (Aluminium, ammonium, calcium, chromium):

Answer 5

Aluminium: For SH it forms a white ppt that is soluable in excess giving a colourless solution. For AA it forms a white ppt that is insoluable in excess.

Ammonium: For SH ammonia gas is produced on warming. For AA nothing happens.

Calcium: For SH it forms a white ppt that is insoluable in excess. For AA it produces very slight or no precipitate.

Chromium: For SH it forms a green precipitate that is soluable in excess. For AA it forms a green precipitate that is insoluable in excess.

Question 6

Test for Cations (Copper(II), Iron(II), Iron(III), Zinc):

Answer 6

Copper(II): For SH it forms a blue ppt that is insoluable in excess. For AA it forms a blue precipitate that is soluable in excess giving a dark blue solution.

Iron(II): For SH it forms a green ppt that is insoluable in excess that turns brown on the surface. For AA it forms a green ppt that is insoluable in excess that turns brown on the surface.

Iron(III): For SH it forms a red-brown ppt that is insoluable in excess. For AA it forms a red-brown ppt that is insoluable in excess.

Zinc: For SH it forms a white ppt that is soluable in excess giving a colourless solution. For AA it forms a white ppt that is soluable in excess giving a colourless solution.