tests for cations

Question 1

aluminium

Answer 1

NaOH
white ppt, soluble in excess giving a colourless solution

NH3
white preciopitate insoluble in excess

Question 2

ammonium

Answer 2

NaOH
ammonia is produced upon warming

Question 3

calcium

Answer 3

NaOH
white ppt, insoluble in excess

NH3
no ppt, or very slight white ppt.

Question 4

chromium (III)

Answer 4

NaOH
green precipitate soluble in excess,

NH3
green ppt, insoluble in excess

Question 5

copper

Answer 5

NaOH
light blue ppt, insoluble in excess

NH3
light blue ppt, soluble in ecxess giving a dark blue solution

Question 6

iron (II)

Answer 6

NaOH
green ppt, insoluble in excess, ppt turns brown upon standing

NH3
green ppt, insoluble in excess, ppt turns brown upon standing

Question 7

iron (IIi)

Answer 7

NaOH
red brown ppt, insoluble in excess

NH3
red brown ppt, insoluble in excess

Question 8

zinc (II)

Answer 8

white ppt, soluble in excess, giving colourless

white ppt, soluble in excess giivng colourless