C12 identification of gases and ions

How can you identify carbonate / CO₃^2- ions?

By adding dilute acid and testing for carbon dioxide gas

How can you identify chloride / Cl^- , bromide / Br^- and iodide / I^- ions in a solution?

By acidifying with dilute nitric acid and then adding aqueous silver nitrate.

How can you identify nitrate / NO₃^- ions in a solution?

Add aqueous sodium hydroxide, then aluminium foil; warm carefully

How can you identify sulfate / SO₄^2- ions in a solution?

Acidify with dilute nitric acid before adding aqueous barium nitrate

What is the positive result for carbonate ions?

Effervescence / carbon dioxide produced

What is the positive result for chloride ions?

White ppt

What is the positive result for bromide ions?

Cream ppt

What is the positive result for iodide ions?

Yellow ppt

What is the positive result for nitrate ions?

Ammonia produced

What is the positive result for sulfate ions?

White ppt

What are the effects of aqueous sodium hydroxide on ammonium / NH₄⁺ ions?

Ammonia is produced on warming

What are the effects of aqueous sodium hydroxide on calcium / Ca⁺² ions?

A white ppt, and it is insoluble in excess

What are the effects of aqueous sodium hydroxide on ions?

A light blue ppt and it is insoluble in excess

What are the effects of aqueous sodium hydroxide on iron(II) / Fe²⁺ ions?

A green ppt and is insoluble in excess, it also turns brown near the surface on standing

What are the effects of aqueous sodium hydroxide on iron(III) / Fe³⁺ ions?

A red-brown ppt and it is insoluble in excess

What are the effects of aqueous sodium hydroxide on zinc / Zn²⁺ ions?

A white ppt and it is soluble in excess giving a colourless solution

What are the effects of aqueous ammonia on calcium / Ca⁺² ions?

No ppt or a very slight white ppt

What are the effects of aqueous ammonia on copper(II) / Cu²⁺ ions?

A light blue ppt and it is soluble in excess leaving a dark blue solution

What are the effects of aqueous ammonia on iron(II) / Fe²⁺ ions?

A green ppt and it is insoluble in excess, ppt turns brown near surface on standing

What are the effects of aqueous ammonia on iron(III) / Fe³⁺ ions?

A red-brown ppt and it is insoluble in excess

What are the effects of aqueous ammonia on zinc / Zn²⁺ ions?

A white ppt and it is soluble excess giving a colourless solution

What is the test and positive result for ammonia / NH₃ gas?

Turns damp red litmus paper blue

What is the test and positive result for carbon dioxide / CO₂ gas?

Turns limewater milky/cloudy

What is the test and positive result for chlorine / Cl₂ gas?

Bleaches damp litmus paper

What is the test and positive result for hydrogen / H₂ gas?

‘Pops’ with a lighted splint

What is the test and positive result for oxygen / O₂ gas?

Relights a glowing splint

What colour does a lithium / Li⁺ ion produce when ignited?

Red

What colour does a sodium / Na⁺ ion produce when ignited?

Yellow

What colour does a potassium / K⁺ ion produce when ignited?

Lilac

What colour does a copper(II) / Cu²⁺ ion produce when ignited?

Blue-green