test for cations and anions

Question 1

Aluminium

Answer 1

Aq NaOH: white ppt soluble in excess giving a colourless solution

Aq ammonia: White ppt. insoluble in excess

Question 2

Ammonium

Answer 2

Aq NaOH: ammonia produced

Question 3

Calcium

Answer 3

Aq NaOH: white ppt. insoluble in excess
Aq ammonia: very slight white ppt.

Question 4

Chromium

Answer 4

NaOH: green ppt. soluble in excess
Ammonia: Green ppt. insoluble in excess

Question 5

Copper

Answer 5

NaOH: light blue ppt. insoluble in excess
NH3: light blue ppt. soluble in excess giving a dark blue solution

Question 6

Iron (ii)

Answer 6

NaOH: green ppt. insoluble in excess
NH3:green ppt. insoluble in excess

Question 7

Iron (iii)

Answer 7

Red-brown ppt. insoluble in excess

Question 8

Zinc

Answer 8

White ppt. soluble in excess giving a colourless solution

Question 9

Test for carbonate

Answer 9

Add dilute acid, producing carbon dioxide and effervescence

Question 10

Test for halides

Answer 10

Acidify with dilute nitric acid, then add aq silver nitrate
Cl : White ppt.
Br : cream ppt
I : yellow ppt

Question 11

Nitrate

Answer 11

Add aqueous sodium hydroxide, then aluminium foil then warm

ammonia produced

Question 12

Sulfate

Answer 12

Acidify with dilute nitric acid, then add barium nitrate

White ppt.

Question 13

Sulfite

Answer 13

add small amount of acidified aq potasium manganate (VII)

Colour change from purple to colourless