How to make a Chemical Garden

The chemical garden was first found by Johann Rudolf Glauber in 1646. He originally used ferrous chloride crystals into a solution of potassium silicate. It works by adding solid transition metal salts to an aqueous solution of sodium silicate (the liquid form of glass) when the metal ions react with the sodium silicate to form a thin membrane of insoluble metal silicate (caused by osmosis), which grows to look like a garden.

Materials Needed:

• A glass container

• Sodium silicate liquid

• Water

• Salt crystals, such as:

  • CaCl2 (calcium chloride)

  • MnCl2 (manganese chloride)

  • CuCl2 (copper chloride)

  • Ni(NO3)2 (nickel chloride)

  • CrCl3 (chromium nitrate)

  • CoCl2 (cobalt chloride)

  • FeCl3 (iron chloride)

Procedure:

Pour water with liquid sodium silicate with ratio of 2mL to 3mL to glass and mix them together

Put a small amount of calcium chloride wherever you like in the liquid glass to get white

Put a small amount of manganese chloride wherever you like in the liquid glass to get pale pink

Put a small amount of nickel chloride wherever you like in the liquid glass to get green

Put a small amount of copper chloride wherever you like in the liquid glass to get light blue-green

Put a small amount of cobalt chloride wherever you like in the liquid glass to get dark blue

Put a small amount of chromium nitrate wherever you like in the liquid glass to get dark green

Put a small amount of iron chloride wherever you like in the liquid glass to get brown

Wait for the garden to grow

Principle:

The garden is formed because transition metal silicates are insoluble in water and are colored. A metal salt forms an insoluble silicate by a double decomposition reaction (anion metathesis). The silicate is a semipermeable membrane. Osmotic increases the pressure within the membrane because the ionic strength inside the membrane is higher than sodium silicate's. This tears the membrane, but the metal's cations react with the silicate's anions and forms a new solid. This keeps happening over and over till it grows. If the density of the fluid inside he membrane was lower than the surrounding solution, it would grow downwards.