Acids predicting metal dissolving

To determine which chloride of iron (FeCla or FeClg) is formed when the metal dissolves in hydrochloric acid, add a few pieces of iron filings, or a small nail, to about 3 c.c. of concentrated hydrochloric acid. While the metal is reacting add a few drops of a solution of a ferrous salt to a solution of sodium carbonate. (5) Record the color of the precipitate. Repeat, using a ferric salt. (6) Record the color of the precipitate. Next pour a few drops of the solution prepared by the action of iron in hydrochloric acid, into a solution of sodium carbonate. (7) What is the color of the precipitate (8) Is the compound formed from the metal and hydrochloric acid a ferrous or a ferric salt (9) From what fact would you have predicted this result ... 

Use the values of E° to predict whether cobalt metal will tend to dissolve in a 1 M solution of acid, H+. Now predict whether cobalt metal will tend to dissolve in a 1 Af solution of zinc sulfate (reacting with Zn+S). 

The dissociation of water coordinated to exchangeable cations of clays results in Brtfnsted acidity. At low moisture content, the Brrfnsted sites may produce extreme acidities at the clay surface-As a result, acid-catalyzed reactions, such as hydrolysis, addition, elimination, and hydrogen exchange, are promoted. Base-catalyzed reactions are inhibited and neutral reactions are not influenced. Metal oxides and primary minerals can promote the oxidative polymerization of some substituted phenols to humic acid-like products, probably through OH radicals formed from the reaction between dissolved oxygen and Fe + sites in silicates. In general, clay minerals promote many of the reactions that also occur in homogenous acid or oxidant solutions. However, rates and selectivity may be different and difficult to predict under environmental conditions. This problem merits further study. 

Predict whether metals that cannot be oxidized by hydrogen ions can dissolve in acids. 

Metallic manganese certainly dissolves readily in 1 mol L-1 aqueous acid, as expected, but in aqueous base a coating of insoluble Mn(OH)2 would form immediately, stopping the predicted reaction. In cases such as aluminum [E° for A13+/A1(s) = -1.67 V], the product Al is soluble in alkali as the aluminate ion Al(OH)4+ but not in neutral water, in which the... 

Copper follows the predictions of its diagram. For this seminoble metal, the potential has to be sufficiently positive to get anodic oxidation. In acidic electrolytes this causes anodic dissolution, and the oxide layers dissolve sufficiently fast so that they are non-protective. For pH > 5.0 these oxides are insoluble, i.e. they are in dissolution equilibrium with the electrolyte. Passivity is achieved when oxide formation occurs at sufficiently positive potentials according to the reactions of Eqs. (1) and (2). 

Some of the effects of toxic chemical mixtures on soil pollution are predictable. Acidic soils dissolve otherwise insoluble metal oxides and salts, thereby increasing available metal concentrations and toxicity to flora and fauna. Available copper content is inversely proportional to increased pH of soiU4 Earthworm mortality in soil polluted by lead increases as pH decreases. I15l The addition of ethylenediaminetetraacetic acid (EDTA) and its disodium salt to soil contaminated with cadmium, lead, and zinc increases the availability of these metals to plants and results in significant increases in the uptake of these in plants. I25l... 

Classical chemistry literature provides comprehensive lists of rate data that can also be applied for predicting abiotic reaction rates of environmental importance when the pathways are well identified. For some reactions, such as hydrolysis or OH radical reactions, enough data are available to determine siructure-reactivity correlations that enable one to interpolate within series of chemically related compounds of known reactivity [for review, see Brezonik (Chapter 4, this volume) and Lyman et al. (1982)]. The aquatic chemist is, however, more often confronted with the fact that many classical studies have been performed in organic solvents, but that the speciation of many dissolved chemicals in aquatic systems may vary with pH (caboxylic acids, phenols, etc.) and with ligand concentrations (e.g., all dissolved heavy metal species) or that the chemical species may be adsorbed on surfaces or absorbed by colloidal organic materials. In all these cases, reaction-rate constants must be determined for each individual aqueous species contributing to the overall kinetics. The equilibrium distribution of these species must also be accounted for. Reductions of the... 

The same information can also be used to predict which metals may dissolve in acid rain. For example, both lead and tin can enter the water supply in acid rain areas, and, for the same reason, acidic water will react with lead water pipes. 

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