Metallic zinc

If metallic zinc is dissolved in this liquid, the following reaction occurs ... 

Metallic zinc was produced in the 13th century A.D. in India by reducing calamine with organic substances such as wool. The metal was rediscovered in Europe by Marggraf in 1746, who showed that it could be obtained by reducing calamine with charcoal. 

The properties of hydrated titanium dioxide as an ion-exchange (qv) medium have been widely studied (51—55). Separations include those of alkaH and alkaline-earth metals, zinc, copper, cobalt, cesium, strontium, and barium. The use of hydrated titanium dioxide to separate uranium from seawater and also for the treatment of radioactive wastes from nuclear-reactor installations has been proposed (56). 

Zinc minerals tend to be associated with those of other metals the most common ate zinc—lead or lead—zinc, depending upon the dominant metal, zinc— copper or copper—zinc, and base metal such as silver. Zinc does occur alone, most often in the northeastern district, and here, as elsewhere, recoverable amounts of cadmium (up to 0.5%) are present. Other minor metals recovered from zinc ores are indium, germanium, and thallium. 

About 20% of the total import bill of a country like Britain is spent on engineering materials. Table 2.2 shows how this spend is distributed. Iron and steel, and the raw materials used to make them, account for about a quarter of it. Next are wood and lumber - still widely used in light construction. More than a quarter is spent on the metals copper, silver, aluminium and nickel. All polymers taken together, including rubber, account for little more than 10%. If we include the further metals zinc, lead, tin, tungsten and mercury, the list accounts for 99% of all the money spent abroad on materials, and we can safely ignore the contribution of materials which do not appear on it. 

For example, if a mixture contains a chemical (i.e., 12 percent zinc oxide) that is a member of a reportable chemical category (i.e., zinc compounds), the notification must include that the mixture contains a zinc compound at 12 percent by weight. Supplying only the weight percent of the parent metal (zinc) does not fulfill the requirement. The customer must be told the weight percent of the entire compound within a listed chemical category present in the mixture. 

The American Zinc Association is a trade organization comprising primary and secondary producers of zinc metal, zinc oxide and zinc dust marketed in the United States. 

The cyclodimerization of 1,3-butadiene was carried out in [BMIM][BF4] and [BMIM][PF(3] with an in situ iron catalyst system. The catalyst was prepared by reduction of [Fe2(NO)4Cl2] with metallic zinc in the ionic liquid. At 50 °C, the reaction proceeded in [BMIM][BF4] to give full conversion of 1,3-butadiene, and 4-vinyl-cyclohexene was formed with 100 % selectivity. The observed catalytic activity corresponded to a turnover frequency of at least 1440 h (Scheme 5.2-24). 

The calculations lor recommended makeup torque assume the use ol a thread compound containing 40% to 60% by weight of linety powdered metallic zinc, or 60% by weight of finely powdered metallic lead, applied thoroughly to all threads and shoulders the use of the modified jackscrew formula as shown in the lAOC Drilling Manual and the API Spec RP 7G (latest addition) and a unit stress of 62,500 psi in the box or whichever is weaker. 

OBasis of calculationa for recommended tool lolnt make-uo torque aaaumed the use of a thread compound containing 40-60% by weight of finely powdered metallic zinc applied thoroughly to all threads and shoulders, and a tensoe stress of 82.500 psi for column 7 and 75.000psi for columns 10.13, and 16... 

Galvanic corrosion is the enhanced corrosion of one metal by contact with a more noble metal. The two metals require only being in electrical contact with each other and exposing to the same electrolyte environment. By virtue of the potential difference that exists between the two metals, a current flows between them, as in the case of copper and zinc in a Daniell cell. This current dissolves the more reactive metal (zinc in this case), simultaneously reducing the corrosion rate of the less reactive metal. This principle is exploited in the cathodic protection (Section 53.7.2) of steel structures by the sacrificial loss of aluminum or zinc anodes. 

For these reasons a somewhat different approach will be adopted here, and an attempt will be made to show how a corrosion reaction may be represented by a well-defined reversible electrochemical cell, although again there are a number of difficulties. Consider the corrosion of metallic zinc in a reducing acid... 

Offshore, both Ag/AgCl and metallic zinc electrodes are used for potential measurements and are also employed for current density surveys undertaken on the offshore platforms and pipelines, as discussed below. It has been found beneficial for offshore applications to install together an electrode of each type on a structure, one acting as a function check on the other. ... 

Painting with aluminium-pigmented paint is considered in Chapter 14 because its properties are essentially those of a paint and not of a metallic coating in this respect aluminium paint differs from zinc-rich paint which can be formulated to provide galvanic properties similar to those of metallic zinc. 

As a third oxidation-reduction example, suppose a strip of metallic zinc is placed in a solution of copper nitrate, Cu(N03)j. The strip becomes coated with reddish metallic copper and the bluish color of the solution disappears. The presence of zinc ion, Zn+2, among the products can be shown when the Cu+2 color is gone. Then if hydrogen sulfide gas is passed into the mixture, white zinc sulfide, ZnS, can be seen. The reaction between metallic zinc and the aqueous copper nitrate is... 

Table 12-11 predicts the cell will operate so as to dissolve metallic zinc and deposit metallic nickel, and its voltage will be +0.51 volt This is exactly what occurs in such a cell. Predicting is fun— let s try it again Another cell we studied is based on reaction (52) ... 

In compounds, the important oxidation numbers of Cr are +2, +3, and +6. In all of these states the chromium ions are colored and, in fact, the element got its name from this property (ichroma is the Greek word for color). The +2 state is not frequently encountered but it can be made quite easily as the beautiful blue chromous ion in solution by dripping a solution containing CrM over metallic zinc. Air has to be excluded since O rapidly converts Cr1-5 back into Cr. ... 

Figure 6. Metal (zinc)/ electrolyte solution (zinc sulfate) phase boundary in the equilibrium state.

For a couple of years 0.25% Hg became the technical standard. It has to be pointed out that the mercury content of the metallic zinc has to be divided by a factor of roughly 10 to give the mercury content based on the total cell weight of an AA (LR-6) cell. These values are sometimes indicated on the cell labels. With decreasing amalgamation, other corrosion inhibitors had to take over the role of mercury. There are numerous papers and patents claiming corrosion-inhibiting activities of elements like A1, In, T1, Cd, Ga, Na, ... 

Chemistry is concerned with the properties of matter, its distinguishing characteristics. A physical property of a substance is a characteristic that we can observe or measure without changing the identity of the substance. For example, a physical property of a sample of water is its mass another is its temperature. Physical properties include characteristics such as melting point (the temperature at which a solid turns into a liquid), hardness, color, state of matter (solid, liquid, or gas), and density. A chemical property refers to the ability of a substance to change into another substance. For example, a chemical property of the gas hydrogen is that it reacts with (burns in) oxygen to produce water a chemical property of the metal zinc is that it reacts with acids to produce hydrogen gas. The rest of the book is concerned primarily with chemical properties here we shall review some important physical properties. 

Self-Test 12.9A Which metal, zinc or nickel, is the stronger reducing agent in aqueous solution under standard conditions Evaluate the standard emf of the appropriate cell, specify the cell with a cell diagram, and write the net ionic equation for the spontaneous reaction. 

An explanation that may be suggested of these facts is that solid solutions of a quadrivalent metal (zinc) in a tervalent metal (aluminium) tend to be unstable because of the difficulty of saturating the valency of isolated quadrivalent atoms by bonds to its lower-valent ligates. With zinc as the solute an increase in free energy at the lower temperatures would accompany the separation into the zinc-poor a phase, in which the versatile zinc atoms tend to assume the valency 3 (less stable, however, for them than their normal valency) in order to fit into the aluminium structure, and the zinc-rich a phase, in which the concentration of zinc atoms is great enough to permit the extra valency of zinc to be satisfied through the formation of Zn-Zn bonds. 

Likewise, triphenyltin hydride reacts with ethylzinc chloride, or triphenyltin chloride with metallic zinc, to give the compound PhaSnZnCl, which is stable in the presence of a strongly coordinating ligand, but, in its absence, apparently undergoes an intermetallic shift of the organic group, so that protic acids react to liberate benzene (272). 

When a strip of zinc metal is added to a solution of copper(II) sulfate, the blue color slowly fades, and the zinc metal is replaced by copper metal (Figure 4-13). As copper ions in the solution are reduced to copper metal, zinc atoms are oxidized to Zn cations. This is an example of a metal displacement reaction, in which a metal ion in solution (Cu ) is displaced by another metal (Zn) by means of a redox reaction. Figure 4-13 also shows molecular views of this displacement reaction. 

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