YR 5th Year of Membership
zinc oxide chemical compound zno, which is nearly insoluble in water but soluble in acids or alkalis. It occurs as white hexagonal crystals or a white powder commonly known as zinc white. Zinc white is used as a pigment in paints; less opaque than lithopone, it remains white when exposed to hydrogen sulfide or ultraviolet light. It is also used as filler for rubber goods and in coatings for paper. Chinese white is a special grade of zinc white used in artists' pigments. Because it absorbs ultraviolet light, zinc oxide can be used in ointments, creams, and lotions to protect against sunburn. Crystalline zinc oxide exhibits the piezoelectric effect, is luminescent, and is light sensitive. Zinc oxide occurs in nature as the mineral zincite. It is used in:
- medical applications
- chemical and biosensor
- food additive
- rubber industries
- electronic materials
The uses of ammonium chloride are many. The Principal use of ammonium chloride is as a fluxing agent for hot dip Galvanizing of steel and in the refining of zinc. Ammonium chloride provides fluxing action by reacting with molten zinc to form a stable melt containing zinc chloride and ammonium chloride.
Other applications for ammonium chloride include electrolyte for plating baths and/or batteries, fertilizer, personal care product formulations, pharmaceuticals, and other applications where the anticaking agent can cause problems.
CaCl2, is a common salt. It behaves as a typical ionic halide, and is solid at room temperature. It has several common applications such as brine for refrigeration plants, ice and dust control on roads, and in concrete. The anhydrous salt is also widely used as a desiccant, where it will adsorb so much water that it will eventually dissolve in its own crystal lattice water. It can be produced directly from limestone, but large amounts are also produced as a by-product of the Solvay process. Because of its hygroscopic nature, the anhydrous form must be kept in tightly-sealed containers. It is used to turn kelp into a solid.
zinc chloride (zncl2) is a colorless or white compound of zinc and chlorine that is extremely hygroscopic. Four crystalline structures have been reported, although in pure form (i. E. Water-free) only the delta (hexagonal close-packed) phase can form. It can be quenched from the melt to form a glassy material. Concentrated aqueous solutions of zinc chloride have the interesting property of dissolving starch, silk and cellulose, so that solution . . .
anhydrous zinc chloride can be prepared from zinc and hydrogen chloride. Zn + 2 hcl(g) → zncl2(s) + h2(g) hydrated forms and aqueous solutions may be readily prepared using standard acid-base methods, or from one of its ores, zinc sulfide: zns(s) + 2 hcl(aq) → zncl2(aq) + h2s(l) commercial samples of zinc chloride typically contain water and zinc oxychloride, the main hydrolysis product. Such samples may be purified as follows: 100 g of crude zncl2 . . .
one use for zinc chloride is as a flux for soldering. This is because of its ability (when molten) to dissolve metal oxides. This property also leads to its use in the manufacture of magnesia cements for dental fillings. Zncl2 has also been used as a fireproofing agent and for etching metals. In the laboratory, zinc chloride finds wide use, principally as a moderate-strength lewis acid. It can catalyse (a) the fischer indole synthesis, and also (b) friedel-crafts acylation reactions involving activated . . .
zinc chloride is an ionic salt, though some covalent character is indicated by its low melting point (275 °c) and its high solubility in solvents such as diethyl ether. It behaves as a mild lewis acid, and aqueous solutions have a ph around 4. It is hydrolyzed to an oxychloride when hydrated forms are heated. In aqueous solution, zinc chloride is a useful source of zn2+ for the preparation of other zinc salts, for example zinc carbonate: zncl2(aq) + na2co . .
Zinc Dust & Powder
Galvanizing fluxes are available with us for every galvanizing operation. Various grades of zinc ammonium chloride fluxes are being manufactured and developed on base of experience in their application in the galvanizing industries.
These fluxes help in
- Saving zinc consumption by reducing ash & dross
- Enabling uniform coating on product
- Providing good metal to metal bounding
- Cleaning the product properly
These qualities tend to make the work economical and essential to use.
Fluxes are used in two different stages
- Water flux or preflux
After the basic surface preparation the work is immersed in solution which makes a layer of zinc ammonium chloride flux on the work so that its oxides are dissolved and it also protect against further oxidation so that when dipped in molten zinc less of zinc ash and zinc dross is formed
- Blanket flux or top flux
In hot dip galvanizing a bath of molten zinc is covered with blanket flux usually referred as top flux and work to be galvanized are lowered into the molten zinc bath through the flux. The flux layer cleans and prepares the work for the reception of a metal coating. It reduce formation of ash in galvanized bath and provides uniform coating on product.