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Reaction of copper with iodine (school experiment)

ID: 125079  |  No.: 351  |  Institut für Chemieinformation

School experiment from Year 5 onwards

Category: Chemical Reactions and Thermodynamics

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Permanent archiving (DOI)

No permanent DOI has been generated for this experiment yet.

Reaction equation

Reaction scheme: Copper + iodine → copper iodide 

Procedure

A very fine, shiny copper mesh weighing at least 2 g is rolled into a small tube and placed in a 100 mL beaker;

50 mL of a 5 per cent Lugol’s solution is added to the beaker. The Lugol’s solution heats up as the exothermic reaction begins. The solution initially becomes cloudy and the brown colour changes, forming a white emulsion. After a few seconds, a voluminous white precipitate forms as the solution clears. Once the reaction has finished or the reaction mixture has cooled, the next step is carried out.

The copper mesh, which is now perforated, is removed from the beaker and rinsed with demineralised water; the copper(I) iodide is filtered through a loose wad of cotton wool using a funnel.

If the filter cake still has a slight yellow tinge, it is washed with a small amount of demineralised water until colourless.

The snow-white filter cake is transferred to a porcelain dish and dried in a desiccator until next week.

Equipment & materials

Test tube, rubber stopper, test tube rack, spatula, plastic dropper pipette

Hazardous substances
Name Formula CAS no. H-statements P-statements Pictograms
Iod 0,01M I₂·aq
Kaliumiodid 10% KI·aq
H372 – Causes damage to the organs <list all affected organs> following prolonged or repeated exposure <specify the route of exposure if there is conclusive evidence that this risk does not arise via any other route of exposure>.
German original: Schädigt die Organe <alle betroffenen Organe nennen> bei längerer oder wiederholter Exposition <Expositionsweg an geben, wenn schlüssig belegt ist, dass diese Gefahr bei keinem anderen Expositionsweg besteht>.
P314 – If you feel unwell, seek medical advice / seek medical assistance.
German original: Bei Unwohlsein ärztlichen Rat einholen / ärztliche Hilfe hinzuziehen.
GHS08
Kupfer(I)-iodid CuI 7681-65-4
H302 – Harmful if swallowed.
German original: Gesundheitsschädlich bei Verschlucken.
H315 – Causes skin irritation.
German original: Verursacht Hautreizungen.
H317 – May cause allergic skin reactions.
German original: Kann allergische Hautreaktionen verursachen.
H318 – Causes serious eye damage.
German original: Verursacht schwere Augenschäden.
H410 – Very toxic to aquatic organisms, with long-term effects.
German original: Sehr giftig für Wasserorganismen mit langfristiger Wirkung.
P273 – Avoid release into the environment.
German original: Freisetzung in die Umwelt vermeiden.
P280 – Wear protective gloves / protective clothing / eye protection / face protection.
German original: Schutzhandschuhe / Schutzkleidung / Augenschutz / Gesichtsschutz tragen.
P302+P352 – IF IT COMES INTO CONTACT WITH THE SKIN: Wash with plenty of water / ...
German original: BEI BERÜHRUNG MIT DER HAUT: Mit viel Wasser / ... waschen.
P301+P312+P330 – IF SWALLOWED: If you feel unwell, call a POISON INFORMATION CENTRE or a doctor. Rinse your mouth.
German original: BEI VERSCHLUCKEN: Bei Unwohlsein GIFTINFORMATIONSZENTRUM oder Arzt anrufen. Mund ausspülen.
P305+P351+P338+P310 – IF IN EYES: Rinse cautiously with water for several minutes. Remove any contact lenses, if possible. Continue rinsing. Call a POISON INFORMATION CENTRE or a doctor immediately.
German original: BEI KONTAKT MIT DEN AUGEN: Einige Minuten lang behutsam mit Wasser spülen. Eventuell vorhandene Kontaktlinsen nach Möglichkeit entfernen. Weiter spülen. Sofort GIFTINFORMATIONSZENTRUM oder Arzt anrufen.
GHS05, GHS07, GHS09
Kupfer, Drahtnetz Cu 7440-50-8

H/P statements: machine translation, with the German original below (authoritative). Name, formula, CAS no. and pictograms are not translated.

Personal protective equipment
  • Safety goggles must be worn.
    German original
    Eine Gestellschutzbrille ist zu tragen.
  • Disposable nitrile gloves are used as splash protection.
    German original
    Als Spritzschutz dienen Nitril-Einmalhandschuhe.
⚠ Hazards
  • by inhalation
    German original
    durch Einatmen
  • through skin contact
    German original
    durch Hautkontakt
  • through eye contact
    German original
    durch Augenkontakt
  • Fire hazard
    German original
    Brandgefahr
  • Risk of explosion
    German original
    Explosionsgefahr
Substitution Substitution 1
The substitution of hazardous substances, as well as their forms of use and methods of application, has been assessed. This experiment is essential for teaching key learning content and may be carried out provided that the restrictions set out in the experiment guidelines are observed and the protective measures specified therein are followed.
There are no known hazardous properties of the substances or other risks that would, in principle, preclude the experiment from being carried out by pupils or teachers. The list of substances in DGUV Information 213-098 at degintu.dguv.de has been taken into account.

The experiment is considerably less dangerous when Lugol’s solution is used instead of iodine as a pure substance!

Literature

Klemeyer, Horst; Safe School Experiments with Iodine (2026), https://doi.org/10.1002/ckon.70002