IGCSE tests for cations

Effect of aqueous sodium hydroxide on aluminium (Al³⁺)

• white ppt, soluble in excess giving a colourless solution

• ammonia produced on warming

• white ppt, insoluble in excess

• green ppt, soluble in excess

• light blue ppt, insoluble in excess

Effect of aqueous sodium hydroxide on ammonium (NH₄⁺)

• green ppt, insoluble in excess

• light blue ppt, insoluble in excess

• ammonia produced on warming

• red-brown ppt, insoluble in excess

• white ppt, soluble in excess, giving a colourless solution

Effect of aqueous sodium hydroxide on calcium (Ca²⁺)

• white ppt, soluble in excess, giving a colourless solution

• white ppt, insoluble in excess

• green ppt, soluble in excess

• red-brown ppt, insoluble in excess

• light blue ppt, insoluble in excess

Effect of aqueous sodium hydroxide on chromium(III) (Cr³⁺)

• white ppt, soluble in excess giving a colourless solution

• light blue ppt, insoluble in excess

• green ppt, soluble in excess

• white ppt, insoluble in excess

• ammonia produced on warming

Effect of aqueous sodium hydroxide on copper (Cu²⁺)

• white ppt, soluble in excess giving a colourless solution

• light blue ppt, insoluble in excess

• green ppt, soluble in excess

• white ppt, soluble in excess, giving a colourless solution

• ammonia produced on warming

Effect of aqueous sodium hydroxide on iron(II) (Fe²⁺)

• white ppt, soluble in excess giving a colourless solution

• light blue ppt, insoluble in excess

• green ppt, insoluble in excess

• white ppt, insoluble in excess

• ammonia produced on warming

Effect of aqueous sodium hydroxide on iron(III) (Fe³⁺)

• white ppt, soluble in excess, giving a colourless solution

• white ppt, insoluble in excess

• green ppt, soluble in excess

• red-brown ppt, insoluble in excess

• light blue ppt, insoluble in excess

Effect of aqueous sodium hydroxide on zinc (Zn²⁺)

• white ppt, soluble in excess, giving a colourless solution

• white ppt, insoluble in excess

• green ppt, soluble in excess

• red-brown ppt, insoluble in excess

• light blue ppt, insoluble in excess

Effect of aqueous ammonia on aluminium (Al³⁺)

• white ppt, soluble in excess giving a colourless solution

• no ppt or very slight white ppt

• white ppt, insoluble in excess

• grey-green ppt, insoluble in excess

• light blue ppt, soluble in excess giving a dark blue solution

Effect of aqueous ammonia on ammonium (NH₄⁺)

• grey-green ppt, insoluble in excess

• light blue ppt, soluble in excess giving dark blue solution

• -

• red-brown ppt, insoluble in excess

• white ppt, soluble in excess, giving a colourless solution