Acid, stannic

Zion-saum, m. list of tin, selvedge, -allure, /. stannic acid, -saureonhydrid, n. stannic anhydride, tin dioxide, -schlich, m. (Ores) tin slimes, fine tin. -schrei, m. = 2Unngeschrei. -seife, /. (Mining) stream tin. -soda, /. sodium stannate. -staub, m. tin dust, -stein, m. tinstone, cassiterite. -sulfid, n. tin sulfide, specif, stannic sulfide, tin(IV) sulfide. -BuUocyanid, 1. tin thiocyanate, specif. 

Stannic acid and stannates Alkylene glycols Aromatic diadds 148... 

Stannic Oxide (White Tin Oxide, Tin Dioxide, Stannic Anhydride, Flowers of Tin Stannic Acid, Cassiterite). Sn02, mw 150.69, white powd, mp 1127°, bp 1800-1900° (subl), d 6.95 g/cc. Sol in coned sulfuric and coned hydrochloric acids, si sol in hot coned aq KOH or NaOH. Prepn is by reacting Sn with coned nitric acid (d 1.41 g/cc) on a w bath forming 0-stannic acid. The 0-stannic acid is then heated to a red heat and converted to Sn02. It is used as a chemical reagent and (see above) as an antifouling, flash and barrel wear reducing additive in propints... 

In 1888, Turpin prepd a series of cool expls which were permissable, by incorporating materials such as alkali chlorides, Na or K bicarbonate (up to 50% content), fluorides, acetates, oxalates, Ba carbonate. 10H2O, chromates, hyposulfites, stannic acid, boric acid, borates, etc, in the expls listed above eg, a) K chiorate 45, double salt of Ca and K acetochlorate 35, tar 18, charcoal 5, and alkali bicarbonate or oxalate I5ps b) K chlorate 15, double salt of K and Amm chlorobichromate 35 K or Na nitrate 10, tar 18, charcoal 5, and K or Na bicarbonate 15ps... 

Sn = 4H this must be borne in mind when calculating the quantities required for the reaction. The stannic chloride forms the complex chloro-stannic acid with hydrochloric acid, which combines with the aniline produced in the reaction ... 

Anhydrous tin(IV) oxide ( Superlite grade) and 6-stannic acid ( Metastannic acid ) were supplied by Keeling Walker Ltd., Stoke-on-Trent. 6-stannic acid paste was prepared at Chinghall Ltd., Milton Keynes, by dispersing Keeling Walker s Metastannic acid, at a level of 73% in a phthalate plasticiser. Colloidal tin oxide, a 25% aqueous dispersion of Sn02> was supplied by Nyacol Products Inc., Ashland, Mass., U.S.A. 

Antimony trioxide, 8-stannic acid (hydrous tin(IV) oxide), zinc hydroxystannate, and zinc stannate were incorporated into the commercial brominated polyester resin at levels of 1,2,5 and 10% by weight. No processing problems were encountered and the samples cured satisfactorily to give rigid, opaque strips. 

Of the tin additives studied, the anhydrous and hydrated zinc stannates, ZnSnO and ZnSn(OH), respectively, are considerably more effective flame-retardant synergists with the bromine present in the plastic than 8-stannic acid (Figure 1). In line with this observation, oxidic tin-zinc systems have previously been found to exhibit superior flame-retardant properties to tin oxides alone (19-22). In addition, ZnSnO, gives higher values of 01 than Sb20, incorporation levels studied, and, in fact, the 1% ZnSnO - containing plastics outperform samples containing 2% Sb O,. 

A further improvement in flame-retardant efficiency is observed when a colloidal dispersion of tin(IV) oxide is incorporated into the polyester. At a 1.5% addition level, colloidal SnO gives an 01 value (49.0) which is markedly higher than that obtained with 5% loadings of either anhydrous SnO, (47.7) or 8-stannic acid (47.9), as powdered additives (Figure 2). In addition to its increased flame-retardant ability, colloidal Sn02 offers the further advantages of translucency in the cured plastic, ease of incorporation and nonsettling in the resin prior to cure. 

The surface area and degree of dispersion in the polymer matrix of the fire-retardant additive has a pronounced effect on its efficiency. Colloidal tin(IV) oxide is significantly more effective, in terms of its flame-retardant ability, than powdered tin(IV) oxide or B-stannic acid. 

Antimony trioxide and 8-stannic acid only exhibit marginal benefits in terms of smoke and CO suppression in this polymer system. 

At the end, the solution, which has become pale yellow, is cooled externally and internally (drop in some ice) and made alkaline with a solution of 150 g. of commercial sodium hydroxide in 300 c.c. of water 1 most of the stannic acid which is at first precipitated goes into solution. The oily base set free is taken up in ether (irrespective... 

White crystals dimorphic sohd exists in both cubic and monoclinic crystalline forms density 3.07g/cm3 melts at 136°C tends to polymerize (similar to stannic acid) forms polymetateUuric acid (H2Te04)n on strong heating sol-... 

Tin(II) and Tm(IV) Hydroxides. Prepare tin (I I) and tin(IV) hydroxides in separate test tubes from solutions of tin chlorides. What reagent should be used to precipitate the tin hydroxides Do tin hydroxides exhibit amphoteric properties What tin compounds are known as a- and P-stannic acids How are they prepared Write the equations of the reactions. 

Preparation of a-Stannic Acid. Add a 10% ammonia solution to a tin(IV) chloride one up to complete precipitation. Wash the product with water by decantation until the chloride ions are removed and filter it off on a Buchner funnel. Test the reaction of a-stannic acid with water, acids, and alkalies. Do the properties of this acid remain the same after prolonged standing or boiling Perform the relevant experiments. 

Preparation of -Stannic Acid. Treat 0.5 g of tin with a 40-50 % nitric acid solution with heating. What do you observe Thoroughly wash the precipitate with water by decantation. See how P-stannic acid reacts with alkalies and acids. Compare the chemical activity of cs- and P-stannic acids. 

A soft, almost silver-white metal, melting at 231° C. Tin dissolves in hot hydrochloric acid with the formation of stannous chloride. Hot concentrated nitric acid converts it into insoluble meta-stannic acid. 

From a consideration of the composition of the halides, and because of the supposed isomorphism of tantalic acid and stannic acid, Rose gave the formulas NbOa and TaOs to anhydrous niobic acid and tantalic acid respectively, but in so doing he repeated an error that had previously been made by Berzelius with regard to vanadium compounds, and overlooked the presence in the halides of an oxygen atom (see p. 24). Blomstrand 8... 

General.—The compounds of niobium are not so numerous as those of vanadium. The following oxides,1 Nb203, Nb02, Nb205, are known, but only the pentoxide gives rise to salts, viz. the niobates.2 The acid character of niobium pentoxide or niobic acid is very weak the niobates are decomposed, for instance, by carbon dioxide, and are readily hydrolysed to the pentoxide. Niobic acid is, in fact, very comparable in its method of preparation and behaviour to silicic acid and stannic acid. 

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