Zinc atomic weight

Complete the table, calculating the atom fraction of zinc, the number of g-atoms in 100 g of alloy, the volume of 100 g of the alloy, and the volume occupied by one g-atom of the alloy. Also, find the partial molar (atomic) volumes of zinc and aluminium at 25°C in an alloy containing 0.75 atom fraction of zinc. Atomic weights of Zn and A1 are 65.38 and 26.96 respectively. 

Under aggressive corrosion conditions it is estimated that the maximum corrosion current density in a galvanised steel sheet will be 6 X 10 A m . Estimate the thickness of the galvanised layer needed to give a rust-free life of at least 5 years. The density of zinc is 7.13 Mg m , and its atomic weight is 65.4. Assume that the zinc corrodes to give Zn " ions. 

This reaction is essential in maintaining a constant pH in blood by the bicarbonate buffer system. Carbonic anhydrase, which contains a single zinc atom in its structure, has a molecular weight of about 30,000. In this structure, zinc is surrounded tetrahedrally by three histidine molecules and one water molecule. The exact role of the catalyst is not known, but it is believed to involve hydrolysis that can be represented as... 

Tanimizu M, Asada Y, Hirata T (2002) Absolute isotopic composition and atomic weight of commercial zinc using inductively coupled plasma mass spectrometry. Anal Chem 74 5814-5819 Van der Walt TN, Strelow FWE, Verheij R (1985) The influence of crosslinkage on the distribution coefficients and anion exchange behavior of some elements in hydrochloric acid. Solvent Extract Ion Exchange 3 723-740... 

ISOTOPES There are 38 isotopes of zinc, ranging in atomic weights from Zn-54 to Zn-83. Just four of these are stable, and those four, plus one naturally radioactive isotope (Zn-70) that has a very long half-life (5x10+ years), make up the element s existence on Earth. Their proportional contributions to the natural existence of zinc on Earth are as such Zn-64 = 48.63%, Zn-66 = 27.90%, Zn-67 = 4.10%, Zn- 68 = 18.75%, and Zn-70 = 0.62%. All the other isotopes are radioactive and artificially produced. 

The atomic weight of bromine.—The at wt. of bromine has been determined by methods which follow in principle those employed for chlorine. A. J. Balard (1826),14 the discoverer of bromine, transformed a known weight of potassium bromide into the sulphate, and also reduced silver bromide to metallic silver by means of zinc the numbers 74 7 and 75 3 were respectively obtained. J. von Liebig (1826)... 

Cavendish found that at 30 inches barometer, and 50° Fahrenheit temperature, one ounce of iron gave 412 and one ounce of zinc gave 202 ounce measures. These volumes are approximately inversely proportional to the present atomic weights of these metals.18... 

Horse liver alcohol dehydrogenase has a molecular weight of 80 000 and is made up of two subunits, each containing two zinc atoms. The subunits are not active in the monomeric form. 

Alcohol dehydrogenase is also obtained from yeast. Yeast alcohol dehydrogenase (YADH) was the first pyridine nucleotide-dependent dehydrogenase to be crystallized by Negelein and Wulff in 1937.1342 YADH is a tetramer of molecular weight 140000-150000. The amount of zinc determined varies,1343 but there are strong indications that the subunits of YADH and LADH have similar structures, including the presence of two zinc atoms. 

Alkaline phosphatase160-164 is a dimeric zinc metalloenzym composed of two identical subunits. The number of zinc atoms per protein molecule varies in different preparations. However, only two seem to be required for catalytic activity. The molecular weight of the monomer has been reported to be 42.000 so the natural dimer would be twice that value. Alkaline phosphatase is a phosphorylating enzyme and has 760 residues per dimer. 

Attempts to use the diethylzinc-pyrogallol (2 1) catalyst to copolymerise propylene sulphide and carbon dioxide failed, since the content of propylene thiocarbonate units in the copolymers formed was small and did not exceed 10 mol.-%. It has also been observed that the presence of carbon dioxide in this copolymerisation system causes a lowering of the molecular weight and yield of the copolymer formed. Thus, it has been suggested that propylene sulphide homopolymerisation was favoured over cross-propagation with carbon dioxide in the presence of a zinc-based coordination catalyst because of higher HSAB symmetry of the system in the former case. The zinc atom in the Zn-S unit of the catalyst is a rather soft acid and will prefer reaction with a soft base such as propylene sulphide rather than with hard carbon dioxide. The presence of a hard acid centre in the triethylaluminium-based catalyst should result in an increase in the affinity of the catalyst towards carbon dioxide [247],... 

That the atomic weight of uranium lead is extremely variable has already been shown. In order to interpret this variability its sources must be studied both geologically and mineralogically. On the geologic side of the question the uranium ore can be divided in to three principal classes, which are sharply distinct. The definitely crystallized varieties of uraninite occur in coarse pegmatites, associated with feldspar, quartz, mica, beryl, and other minor accessories. The massive pitchblende is found in metalliferous veins, together with sulphide ores of copper, lead, iron, zinc, and so forth. As for camotite, that is a secondary mineral, found commonly as an incrustation on sandstone, and often, also upon fossil wood. There may be other modes of occurrence, but these are the most distinctive. 

The atomic weight of zinc is therefore 4.09 X 16 = 65.4 if our assumption of the 1 1 ratio is correct. Therefore 65.4 grams of zinc is the gram atomic weight of this element, and it likewise contains 6.06 X 1023 actual atoms. 

The combining ratio by weight of zinc and sulphur is 2.039 1. Assuming the knowledge that the atomic weight of zinc is 65.4 and that zinc and sulphur combine in the 1 1 atomic ratio, find the atomic weight of sulphur. 

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