Sodium zincate

Zinc is electrodeposited from the sodium zincate electrolyte during charge. As in the zinc/bromine battery, two separate electrolytes loops ("posilyte" and "nega-lyte") are required. The only difference is the quality of the separator The zinc/ bromine system works with a microporous foil made from sintered polymer powder, but the zinc/ferricyanide battery needs a cation exchange membrane in order to obtain acceptable coulombic efficiencies. The occasional transfer of solid sodium ferrocya-nide from the negative to the positive tank, to correct for the slow transport of complex cyanide through the membrane, is proposed [54],... 

In 0-level qualitative analysis, unknown cations are identified by reacting them with aqueous sodium hydroxide and/or aqueous ammonia. For example, zinc salt solutions react with aqueous sodium hydroxide to form a white precipitate, zinc hydroxide, which in turn will react with excess aqueous sodium hydroxide to form a colourless solution of sodium zincate, a complex salt. However, 25% of the 915 students thought that when sodium hydroxide solution was added to a solution of a zinc salt, a displacement reaction resulted leading to the formation of a precipitate... 

In zinc chloride, zinc is present as the positive cation, Zn2+, whereas in sodium zincate, zinc is present as part of the negative zincate anion, (Zn02)2-. In the present context, reference must be drawn to water. It can accept a proton and can act as a base similarly, it can part with a proton and can act as an acid. Thus, it has an amphoteric (dual) nature. Water can function as a base in the presence of acids stronger than itself and as an acid in the presence of bases stronger than itself. As an example in the former category reference may be drawn to the reaction,... 

With Zinc.—If a solution of caustic soda in water is brought into contact with metallic zinc, chemical reaction takes place, with the production of sodium zincate and hydrogen. The reaction is expressed in the following equation —... 

Evaporate the sodium zincate solution to a volume of about 100 ml, and then add a sodium sulphide solution to it up to complete precipitation of the zinc sulphide. After settling, suck off the precipitate onto a glass filter and wash it with a small amount of water (10-15 ml). Dry the precipitate in a drying cabinet at 70-80 °C. 

ADD SMALL AMOUNT OF NaOH SOLUTION TO DILUTED TINNERS FLUID (ZnCI,). Zn(OH), IS FORMED. ADD MORE NoOH. PRECIPITATE DISSOLVES WITH FORMATION OF SODIUM ZINCATE (Na.Zn O,). 

Support a 1-litre three-necked flask, equipped with a sealed stirrer unit and a reflux condenser, on a water bath, and place a solution of 65 g of sodium hydroxide in 150 ml of water, 50 g (41.5 ml, 0.41 mol) of pure nitrobenzene and 500 ml of methanol in the flask. Add 59 g (0.9 mol) of zinc powder (90% purity see Section 4.2.50, p. 467) to the mixture, start the stirrer and reflux for 10 hours (1). Filter the mixture while hot, and wash the precipitate of sodium zincate with a little methanol. The strongly alkaline filtrate is not always clear render it neutral to litmus by the cautious addition of concentrated hydrochloric acid, and filter again. Distil off the methanol from the filtrate, cool the residue in ice and filter off the solid azobenzene. The crude azobenzene contains occluded zinc salts. To remove these, add the crude product to 100 ml of 2 per cent hydrochloric acid, warm to about 70 °C... 

A large number of compounds used as catalysts in acid-ion lactam polymerization are known. These include alkalis, alkali-earth metals, hydrates, Grignard reagents, lithium oxide, various hydroxides and carbonates, sulfates, halides, sodium zincate, alkaline salts of different acids, i.e., compounds that cause the formation of lactam acid ion in the reactive medium. The mechanism of polymerization in the presence of sodium-lactam- salt compounds is largely known. 

Among the oxides and hydroxides which exhibit the power of acting both as acid and basic compounds are cupric hydroxide, Cu(OH)2, which dissolves in a concentrated solution of potassium hydroxide with a dark blue colour zinc and cadmium hydroxides, which dissolve in excess of alkali sodium zincate has been separated by addition of alcohol, and is precipitated in white needles of the formula Na2ZnO .8H20 and aluminium hydroxide, which dissolves in alkali, forming an aluminate, MA102 ... 

Of the above precipitates, zinc hydroxide alone dissolves freely in excess of the reagent. It forms the soluble salt sodium zincate, Na2Zn02, and it is thus an amphoteric substance like aluminum hydroxide (compare Experiments 2, 3, 4, and 5, page 217). 

When the concentration of NaOH is low the sodium zincate (Na2Zn(OH)4) precipitates as zinc hydroxide according to... 

As stated earlier, lower leaching temperatures result in increased surface areas of skeletal catalysts. Furthermore, slowing the leaching process by the addition of sodium zincate to the leach solution leads to higher surface areas. Thus leaching of CuA in 6.1 M NaOH containing 0.62 M sodium zincate at 274 K leads to a catalyst of surface area of 58.1 m2 g 1 compared with a surface area of 28.0 m2 g 1 when no sodium zincate is present. 

A 5-1. three-necked round-bottomed flask, fitted with a mercury-sealed stirrer and a reflux condenser, is placed on a steam cone. In the flask are placed 250 g. (208 cc., 2 moles) of nitrobenzene, 2.5 1. of methanol, and a solution of 325 g. (8.1 moles) of sodium hydroxide (Note 1) in 750 cc. of distilled water. To the mixture is added 265 g. (4.1 moles) of zinc dust (Note 2), the stirrer is started, and the mixture is refluxed for ten hours (Note 3). The mixture is filtered while hot, and the precipitate of sodium zincate is washed on the filter with a little warm... 

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