Tuesday, November 16, 2010

Zinc Oxide

Zinc Oxide has chemical formula ZnO with molecular weight of 81.83, has appearance white powder. Zinc Oxide has melting point of 1975 oC, specific gravity 5.4 – 5.6, bulk apparent 0.6 – 0.7 g/cm3, solubility in water and alcohol almost null, but soluble in acetic and mineral acid, ammonium chloride, alkalis, and ammonium hydroxide.

Zinc Oxide produced by indirect process has distinct advantages over material produced by other processes, these advantages as follows:

1. consistently fine particle sizes
2. consistently high purity
3. consistently good white color

Zinc oxide is uniform particle size, purity and color enable users to apply standard formulations without the complication of having to vary formulation to accommodate variations common to material from many other processes.

Zinc oxide powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber, lubricants, paints, ointments, adhesives, sealants, pigments, food as zinc nutrient, batteries, ferrites, fire retardants, first aid tapes, etc.

Zinc oxide can change to liberate oxygen because of heat at temperature at about 800oC and also degraded by most acids, such as hydrochloric acid.

ZnO + 2 HCl → ZnCl2 + H2O

Also in base can be degraded, the solid give soluble zincates:

ZnO + 2 NaOH + H2O → Na2(Zn(OH)4)

ZnO also forms cement like products when treated with phosphoric acid, related materials are used in dentistry. Zinc oxide reacts with hydrogen sulfide to give the sulfide, this reaction is used commercially in removing H2S using ZnO powder (e.g. as deodorant).

ZnO + H2S → Zn S + H2O

Find another articles over internet: