8.3.2 Metal Hydroxides

• What can sodium hydroxide solution be used to identify?

  Metal ions (cations).
• What colour precipitate does aluminium form?

  White but redissolves to colourless.
• What colour precipitate does calcium form?

  White.
• What colour precipitate does magnesium form?

  White.
• What colour precipitate does copper(II) form?

  Blue.
• What colour precipitate does iron(II) form?

  Green.
• What colour precipitate does iron(III) form?

  Brown.