Stopping corrosion

Zinc protects iron from corrosion!

Difficulty:
Danger:
Duration:
1 day
Stopping corrosion

Reagents

Safety

  • Put on protective gloves and eyewear.
  • Conduct the experiment on the plastic tray.
General safety rules
  • Do not allow chemicals to come into contact with the eyes or mouth.
  • Keep young children, animals and those not wearing eye protection away from the experimental area.
  • Store this experimental set out of reach of children under 12 years of age.
  • Clean all equipment after use.
  • Make sure that all containers are fully closed and properly stored after use.
  • Ensure that all empty containers are disposed of properly.
  • Do not use any equipment which has not been supplied with the set or recommended in the instructions for use.
  • Do not replace foodstuffs in original container. Dispose of immediately.
General first aid information
  • In case of eye contact: Wash out eye with plenty of water, holding eye open if necessary. Seek immediate medical advice.
  • If swallowed: Wash out mouth with water, drink some fresh water. Do not induce vomiting. Seek immediate medical advice.
  • In case of inhalation: Remove person to fresh air.
  • In case of skin contact and burns: Wash affected area with plenty of water for at least 10 minutes.
  • In case of doubt, seek medical advice without delay. Take the chemical and its container with you.
  • In case of injury always seek medical advice.
Advice for supervising adults
  • The incorrect use of chemicals can cause injury and damage to health. Only carry out those experiments which are listed in the instructions.
  • This experimental set is for use only by children over 12 years.
  • Because children’s abilities vary so much, even within age groups, supervising adults should exercise discretion as to which experiments are suitable and safe for them. The instructions should enable supervisors to assess any experiment to establish its suitability for a particular child.
  • The supervising adult should discuss the warnings and safety information with the child or children before commencing the experiments. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
  • The area surrounding the experiment should be kept clear of any obstructions and away from the storage of food. It should be well lit and ventilated and close to a water supply. A solid table with a heat resistant top should be provided
  • Substances in non-reclosable packaging should be used up (completely) during the course of one experiment, i.e. after opening the package.

Step-by-step instructions

Take three iron nails Fe. Connect the first nail to the less reactive metal copper Cu, leave the second one as is, and connect the third one to the more reactive metal zinc Zn.

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Prepare three vials of water, in which our nails are supposed to rust.

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Electrons will move through the wires from the more reactive metal to the less reactive metal. As a result, the more reactive metal will corrode more intensively, while the less reactive metal will not show so much damage.

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In the Fe + Cu pair, the iron Fe is more reactive than copper Cu. So it rusts even faster than the iron Fe on its own. While in the Fe + Zn pair, the more reactive zinc Zn takes the hit, protecting its iron Fe partner from corrosion.

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Disposal

Dispose of solid waste together with household garbage. Pour solutions down the sink. Wash with an excess of water.

Scientific description

The oxygen O2 dissolved in water easily takes electrons e from iron Fe. The iron atoms thus develop an electron deficit. They become ions Fe2+ and Fe3+ and react with water. As a result, a mixture of iron oxides and hydroxides is formed; we call this mixture rust.

Oxygen O2 readily takes electrons e from iron Fe, but if a more reactive metal is connected to the iron (zinc Zn, for example), the iron can make up for its electron deficit by taking electrons from the more reactive zinc. As a result, zinc atoms, not iron atoms, will ultimately lose electrons overall. The zinc atoms turn into zinc ions Zn2+ and react with water H2O, forming zinc hydroxide Zn(OH)2. This is how zinc "takes the hit."

The interactions of metals of varying reactivity are used to protect metal constructions from corrosion. For example, special zinc plates are attached to the iron bodies of ships. These plates give their electrons to the iron structure of their ship and corrode instead of it, sacrificing themselves and allowing the iron to remain relatively undamaged.