Chemical garden

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A chemical garden (or crystal garden) is a simple experiment in chemistry, usually performed by adding one or more metal salts, such as copper(II) sulfate, iron(II) chloride, cobalt(II) chloride, nickel(II) sulfate to an aqueous solution of sodium silicate or potassium silicate. This results in growth of "plant" like forms in minutes to hours.

Preparation

A transition metal salt is added in the sodium silicate solution, resulting in the formation of a transition metal silicate, which grows upwards if the density of the fluid inside the resulting semi-permeable membrane is low, and downwards if the density is high.

The resulting garden should not be shaken, since the "plants" are very delicate and will break. The life of garden can be extended by slowly adding water at a very slow rate, after the growth has ceased.

Salts used

Salt Color
Aluminium potassium sulfate White
Calcium chloride White
Cobalt(II) chloride Purple
Chromium(III) chloride Green
Copper(II) sulfate Blue
Iron(II) sulfate Green
Iron(III) chloride Orange
Manganese(II) chloride Pink
Nickel(II) sulfate Green
Zinc chloride White

Other types of chemical gardens

Charcoal crystal garden

This chemical garden does not require sodium silicate. Instead, salt crystals are grown on charcoal substrates. Other porous materials can also be used, such as brick, cork, sponge, porous rock, pumice. For this experiment you will need charcoal briquettes, ammonia, distilled water, uniodized salt, bluing, and food coloring.[1]

Handling

Safety

While sodium silicate is not very toxic, and only somewhat irritating, some salts used, like cobalt salts are harmful and proper protection should be worn when working.

Storage and disposal

Chemical gardens do not store well over time.

Generally, chemical gardens don't require special disposal and can be simply dumped in trash. If toxic metal compounds have been used, special disposal may be required.

References

  1. http://chemistry.about.com/cs/growingcrystals/ht/charcoalgarden.htm

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