Carbonates basic copper

A reddish powder with pretty metal lustre. The atomic weight is 63.55. Specific gravity 8.9 it melts at 1083°C and boils at 2595°C Gradually it is coated with a film of basic copper carbonate in the wet state by the action of moisture and carbon dioxide gas in the air. When it is added to a composition which contains ammonium perchlorate, a pretty blue flame is obtained 5% copper powder is adequate. Neverthless ammonium perchlorate reacts with copper powder generating heat and ammonia gas in the presence of moisture, and the composition must be well protected from the moisture. 

Basic copper carbonate cannot produce such a good blue as copper acetoarsenite, but it is not easily scattered and is not so poisonous. 

It is well suited to ammonium perchlorate compositions or high temperature flame compositions, where HCl gas is produced in the flame. 

Manufacture. It is obtained by gradually adding a calculated amount of ammonium carbonate to copper sulphate solution in water. At first various forms of blue green precipitates occur in the solution, but they gradually change to the crystaline form of basic copper carbonate 11.  

C H3(CH2) 11(CHOH)3COOH. This is a chain compound, but another kind of ring compound, C15K20O6, is contained in shellac. One analysis showed that shellac contained 7.00% C, 23.87% O and 9.00% H, and a formula C16H26O4 was applied to it. 

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Basic copper carbonate is essentially iasoluble ia water, but dissolves ia aqueous ammonia or alkaU metal cyanide solutions. It dissolves readily ia mineral acids and warm acetic acid to form the corresponding salt solution. 

The pale green product is called basic copper carbonate and is responsible for the green patina of copper and bronze objects (Fig. 16.13). The patina adheres to the surface, protects the metal, and has a pleasing appearance. 

FIGURE 16.13 Copper corrodes in air to form an attractive pale green layer of basic copper carbonate. This patina, or incrustation, passivates the surface, which helps to protect it from further corrosion. 

The reddish metal was already known in prehistoric times. It occasionally occurs as a native metal, but mostly in conspicuous green ores, from which it is extracted relatively easily. It is convenient to work, but not very hard. Not very optimal as a tool ("Otzi the Iceman" had a copper axe with him). Only through the addition of tin is the more useful bronze obtained. Its zinc alloy is the versatile and widely used brass. Copper is one of the coinage metals. Water pipes are commonly made of copper. Its very good thermal and electrical conductivity is commonly exploited (cable ), as well as its durability (roofs, gutters), as the verdigris (basic copper carbonate) protects the metal. Cu phthalocyanines are the most beautiful blue pigments. Seems to be essential to all life as a trace element. In some molluscs, Cu replaces Fe in the heme complex. A 70-kg human contains 72 mg. 

Blue Mountain blue or Basic copper carbonate... 

Azurite (basic copper carbonate) Bright blue... 

Basic copper carbonate is used as a pigment in paint and varnish as a fungicide for seed treatment as an insecticide in pyrotechnics and in the manufacture of other copper salts. The compound is also added in small quantities to animal and poultry feed to supply nutritional copper requirements. 

Basic copper carbonate occurs in nature as minerals, malachite and azu-rite. While the carbonate to hydroxide molar composition ratio in natural malachite is 1 1, the ratio in azurite [2CuC03 Cu(OH)2] is 2 1. 

Copper oxide (CuO), basic copper carbonate - CuCO 3 C u(OH) 2, and copper sulfate - available commercially as CuS0 5H2O - are... 

Mnterial is actually basic copper carbonate, 2 CuCOj-CuCOH) ... 

Heap (dump) acid leaching of copper sulfide ores is possible with the aid of microbial oxidation. Not all copper minerals are sulfidic, however— malachite, azurite, and chrysocolla are basic copper carbonates—and sulfuric acid heap leaching of low-grade copper carbonate ores can give solutions from which the Cu2+ ion can be separated by solvent extraction (Section 17.3) and copper metal obtained by electrowinning. 

How Acids with the Same Normality Affect a Metal. Pour identical amounts (10 ml) of 1 V hydrochloric, sulphuric, and acetic acid solutions into three test tubes. Take three identical pieces of magnesium (not over 0.2 g) or identical masses (not over 0.2 g) of basic copper carbonate and simultaneously introduce them into the tubes with the acids. Note in which acid the magnesium (or carbonate) dissolves more rapidly. Why ... 

See how the carbonates of various metals change when heated. For this purpose, roast the following salts in test tubes basic copper carbonate, magnesium, calcium, and sodium carbonates, and sodium bicarbonate. Pass the evolving gas into lime water. Write the equations of the reactions. Explain why the thermal stability of the studied carbonates differs. 

By passing chlorine through a suspension of basic copper carbonate in aqueous selenious acid, copper selenate and copper chloride pass into solution ... 

BASIC SALT. A compound belonging to the categories of both salts and bases, because it contains OH (hydroxyl) or O (oxide) as well as the usual positive and negative radicals of normal salts. Among the best examples are bismuth subnitrate, often written BiONO, and basic copper carbonate, Cu2 (OH)2CO.). Most basic salts arc insoluble in water and many arc of vaiiable composition. 

Seip 32 is a material with deep green colored stains (9). The infrared spectrum of the green colored sample (Figure 17) does not appear similar to malachite (basic copper carbonate) as do the Etowah materials, but it is similar to verdigris (IRUG 00152) (19), which is composed of acetates and diacetates of copper. Thus the mineral replacement of the two fabrics is somewhat different. Whether that difference is due to the environment of mineralization or to the previous chemical composition of the textiles cannot be determined. 

A number of attempts have been made to understand the mechanism of the adsorption of chelates on oxide minerals. For instance, IR spectroscopic studies10 have indicated the presence of a basic monosalicylaldoximate copper complex as well as the bis-salicylaldoximate complex on the surface of malachite (basic copper carbonate) treated with salicylaldoxime. However, other workers4 have shown that the copper chelate is partitioned between the surface and dispersed within the solution, and that a dissolution-precipitation process is responsible for the formation of the chelate. Research into the chemistry of the interaction of chelating collectors with mineral surfaces is still in its infancy, and it can be expected that future developments will depend on a better understanding of the surface coordination chemistry involved. 

Of the arsenic-free pigments the best known are Mountain green and blue (basic copper carbonates) and Bremen green and blue (copper hydroxides) use is made, but less commonly, of greens based on the basic acetate, basic sulphate, oxychloride and stannate of copper, already mentioned. All these products may be adulterated with the usual extraneous white substances, such mixtures being given special names. 

Symes J.L. and Kester D.R. (1984) Thermodynamic solubility studies of the basic copper carbonate mineral, malachite. Geochim. Cosmochim. Acta 48, 2219-2229. 

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