Hydroxide Ion Test

• (Copper) Cu2+:

  observation with small amount of sodium hydroxide: blue ppt.

  observation with excess amount of sodium hydroxide: no further change
• (Iron II) Fe²⁺:

  observation with small amount of sodium hydroxide: green ppt.

  observation with excess amount of sodium hydroxide: no further change
• (Iron III) Fe³⁺:

  observation with small amount of sodium hydroxide: brown ppt.

  observation with excess amount of sodium hydroxide: no further change
• Aluminium (Al³⁺):

  observation with small amount of sodium hydroxide: white ppt.

  observation with excess amount of sodium hydroxide: ppt. re-dissolves
• Calcium (Ca²⁺):

  observation with small amount of sodium hydroxide: white ppt.

  observation with excess amount of sodium hydroxide: no further change
• Magnesium (Mg²⁺):

  observation with small amount of sodium hydroxide: white ppt.

  observation with excess amount of sodium hydroxide: no further change
• Hydroxide Ion Tests are used to test the presence or absence of some metal ions in a compound