Adventures in Science and Technology - Electroplating Project

[Chemistry]

This project idea comes to you from Venture Engineering and Science Camp in Hamilton, Ontario.

To investigate electrolysis by electroplating copper from a penny to another metal object.

Did you know... The ancient Greeks would not have known that electrons even existed; they had discovered nothing smaller than the atom. Nowadays, the smallest-known particle is the quark, but who knows what miniature universes we may still discover?

Everything in the world is made up of millions of tiny atoms. Atoms are made up of even smaller particles called electrons, protons, and neutrons. Protons and neutrons are found in the centre of each atom, and the electrons circle around the protons. Each electron has an electric charge, and this charge, which is negative, is the fundamental cause of electricity. Protons have a positive charge and neutrons have no charge.

Current electricity is produced by electrons on the move in a continuous, unbroken path or "circuit". It can only exist in a conductor, which is a material such as a metal that allows electrons to pass through it. To make these electrons move, a source of energy or a driving force is needed. Chemical energy is the source of power in a battery-powered circuit.

Background Terms:

Current: produced by electrons moving in wires
Electricity: a continuous, unbroken path or circuit of electrons which produces one of the most fundamental forces that holding all matter together
Electrochemistry: a type of chemistry involving processes that convert electrical energy into chemical energy and vice versa
Electrode: a conducting material, usually a metal through which electrons enter or leave the conducting medium
Electrolysis: chemical reaction caused by passing an electric current through a liquid, making the molecules of the liquid split up
Electrolyte: a compound which, when in solution, produces ions (atoms with electrical charge)
Electroplating: the process of covering an object made of some metal with a layer of another metal by means of electrolysis

1 plastic container
2 pieces of insulated wire (approx. one foot each)
1 battery
15 mL of salt
200 mL of vinegar
1 penny
1 other metal object (e.g. a washer)

Pour 200 mL of vinegar into a plastic container and add 15 mL of salt. Stir until the salt is totally dissolved.
Wrap one end of one wire around the penny and tape the other end of the same wire to the positive end of the battery.
Wrap one end of the other wire around the other metal object and tape the other end to the negative terminal of the battery.
Submerge both objects into the container. Make sure the wires do not cross.
Wait and watch.
If any black residue appears (copper oxide) wipe it off to speed up the process.

When you add salt to the vinegar, the salt molecules separate (technically called "dissociate") into their component parts: positive sodium ions and negative chloride ions. (The chemical name for salt is sodium chloride because it is made up of sodium and chloride atoms.) The sodium chloride is called the electrolyte because it provides these charged atoms, called ions. In this activity, two electrodes (the pennies and the washers) are dipped into the electrolyte. The electrodes, which are metals that can conduct electricity, are attached to the battery by wires. As in magnets, opposite charges attract. Since the non-copper metal washer (zinc, nickel, etc.) is connected to the negative end of the battery, the positive copper ions are attracted to the non-copper metal, producing a copper coating on it. This process is called electroplating.

Electroplating is more than a century old. You can see many examples of electroplating around you. The "tin can", for example, is actually a steel can that has been plated with a protective layer of tin. Nowadays many "tin cans" are actually plated with chromium instead of tin, because it is more resistant to corrosion. New applications for electroplating are being experimented with right now. To replace worn or damaged human joints by synthetic ones, doctors need strong, light, and resistant materials. One material that has shown promise in experiments is made by plating a light-weight alloy with a thin coat of tantalum.

Produced by Galactics.
Comments: galactics@spacesim.org.
Last updated on 14 August 1998.