Identification of Cations

By Rochelle Campbell

Identification of Cations

​DONE BY: MISS ROCHELLE CAMPBELL

At the end of this topic you should be able to:

1. ​Identify the ions Pb²⁺, Al³⁺, Ca²⁺, Zn²⁺, Fe²⁺, Fe³⁺, Cu²⁺ by colour and solubility of the hydroxides in aqueous sodium hydroxide.

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2. Write ionic equations for the reactions above. ​

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Poll

Did you read over the notes on 'Qualitative Analysis'

• Yes

• No

• Not thoroughly

Multiple Choice

If a white precipitate forms, which is insoluble in excess sodium hydroxide, a Group II cation may be present.

• Calcium

• Lead

• Copper

• Sodium

Draw

Write an ionic equation for the following a Group II cation reacting with excess sodium hydroxide (include state symbols)

Multiple Select

When a white precipitate is formed that dissolves when excess sodium hydroxide is added to give a colourless solution. Identify the ions that may be present:

• Aluminum

• Lead

• Zinc

• Sodium

Draw

Write an ionic equation when Aluminum is reacting with sodium hydroxide not in excess and another ionic equation when sodium hydroxide is in excess

Multiple Choice

Identify the cation that gives a coloured precipitate of 'grey-green'

• Fe(OH)₂

• Fe(OH)₃

• Cu(OH)₂

Multiple Choice

Identify the cation that gives a coloured precipitate of 'Pale blue'

• Fe(OH)₂

• Fe(OH)₃

• Cu(OH)₂

Open Ended

When Fe³⁺ reacts with excess sodium hydroxide to form Fe(OH)₃.

Type the colour precipitate that will be seen by the experminter.