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Technical data


Iron cloride test / Formation of verdigris

Article no: P7172900
Principle

Short-chain carboxylic acids react with Fe3+ ions to form red-coloured complexes of the type [Fe3(OH-)2(HCOO-)6]1+[HCOO]1-, which decompose to brown iron(II) oxyhydrate on heating. Verdigris is basic copper acetate Cu(CH3COO)2•Cu(OH)2. Naturally occurring verdigris forms in the presence of CO2, CO and moisture in the air with basic copper carbonate as intermediate. The verdigris formation is not very specific, as the other short-chain carboxylic acids also form similarly structured copper compounds.

It could be useful to show in a parallel demonstration experiment that pure acetic acid does not give a red-colouration. Working in groups is recommended for this experiment, so that the time until the formation of verdigris can be utilized. One group can carry out the iron chloride test while a second group starts the experiment on verdigris formation.

Learning objectives

  • Formic acid and acetic acid exhibit some reactions typical for carboxylic acids, and can so be distinguished from other acids.
  • Typical reactions are the red colouration on the addition of iron(III) chloride and the formation of verdigris.

Benefits

  • Easy teaching and efficient learning by using interactive experimentation PHYWE-Software
  • Experiment is part of a complete solution set with experiments for the topic Organic Chemistry matched with international curriculum: all topics are covered

 

Scope of delivery

Crucible tongs, 200 mm, stainless steel 33600-00 1
Beakers, Boro, low form, various sizes 46060-00 2
Beakers, Boro, low form, various sizes 46054-00 1
Test tube,180x22 mm, PN19 MAU-17080101 1
Graduated cylinder, 10 ml, plastic 36636-00 1
Test tube, laboratory glass, various lengths, 100 pcs. 37658-10 1
Test tube brush w. wool tip,d20mm 38762-00 1
Test tube rack, wood, for 6 tubes d= 22mm MAU-20042200 1
Test tube holder, up to d 22mm 38823-00 1
Protecting glasses, clear glass 39316-00 1
Tweezers, l = 130 mm, straight, blunt 64610-00 1
Scissors, l = 110 mm, straight, point blunt 64616-00 1
Pipette with rubber bulb 64701-00 1
Formic acid 75% 250 ml 30023-25 1
Iron-III chloride, 250 g 30069-25 1
Copper foil, 0.1 mm, 100 g 30117-10 1
Sodium acetate trihydrate, 250 g 30149-25 1
Sodium carbonate, anhyd. 1000 g 30154-70 1
Sodium formate 250 g 30156-25 1
Indicator paper, pH1-14, roll 47004-02 1
Water, distilled 5 l 31246-81 1
Acetic acid 99...100%, pure 1 l 31301-70 1
Butane burner with cartridge, 220 g 32180-00 1
Erlenmeyer flask, stopper bed, 100 mlSB 19 MAU-EK17082002 1

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