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Zinc oxide is white, powdery substance. It is insoluble in water. It will decompose before melting when heated to 1975°C, or to 950°C with carbon.
Crystalline zinc oxide is thermochromic, changing from white to yellow when heated and in air reverting to white on cooling. This color change is caused by a small loss of oxygen to the environment at high temperatures to form the non-stoichiometric Zn1+xO, where at 800 °C, x = 0.00007.
Like most chemicals, zinc oxide can be purchased from scientific suppliers like Elemental Scientific in pure form. It can also be purchased from art and ceramic suppliers, since it is used as a pigment and in glazes.
A more clean method involves electrolyzing a solution of sodium bicarbonate with a zinc anode. Zinc hydroxide and hydrogen gas are produced. The zinc hydroxide is pyrolyzed to zinc oxide.
It is also a side product of zinc melting. If the floating slag becomes yellow at high temperatures, then it contains zinc oxide.
- Thermochromism demonstration
- Make zinc oxide eugenol
- Make zinc metal
- Grow large crystals via hydrothermal growth
- Ceramic materials
Zinc oxide is non-toxic, but it's generally best to avoid breathing it in as it could potentially irritate the airways. Impure zinc often contains cadmium, which is extremely toxic to oneself and the environment.
Zinc oxide does not require special storage, though it should be kept away from any acidic vapors.
Zinc oxide poses little toxicity to the environment, though it may contain traces of cadmium.