2 Chemistry -- Heavy Metals: Copper

Why is calcium carbide mixed with sand?

1 Answers

Calcium carbide ( $C a C_{2}$ ) reacts with water to produce acetylene ( $C_{2} H_{2}$ ):

$C a C_{2} (s) + 2 H_{2} O (g) ⇋ C a (O H)_{2} (s) + C_{2} H_{2} (g)$

When it is used to produce acetylene, however, it is mixed with sand because the reaction between CaC₂ and H₂O is quite exothermic and this causes two issues:

the as-produced acetylene is very flammable;
the Ca(OH)₂ byproduct.

Both can be circumvented by adding sand to the reaction mixture in order to absorb the heat excess and let calcium hydroxide react with it to form calcium silicate, which removes it:

Ca(OH)₂ + SiO₂ → CaSiO₃ + H₂O

This, in turn, produces even more water that speeds up the production of acetylene itself.

Why is the froth flotation method selected for the concentration of sulphide ores?

The surface of sulphide ores is preferentially wetted by heavy oils like turpentine or pine oil while the gangue is wetted by water hence, froth floatation method is selected for concentration of sulphide ores.

What is the composition of ‘Copper matte’?

Copper sulphide contains some amount of iron sulphide as impurities which is called copper matte.
Copper matte mainly consists of cuprous sulphide and little ferrous sulphide.

How is blister copper obtained from copper pyrite?

The molten mass of copper is cooled then dissolved SO2 gas is obtained in the form of a bubble. This gives the shape of a blister to the surface of solidified copper. For this reason, it is also called blister copper which contains 2% impurities like Ag, Ni, Zn, etc. Then it is taken for purification.

Write a note highlighting the important fact about the chemistry of blue vitriol.

USES OF BLUE VITROL

Antiseptic agent

In electroplating processes.

Antifungal agent for topical use

Treatment of copper deficiency

Etching - Copper sulfate is also used to etch zinc plates for intaglio printmaking.

Dyes - Copper sulfate can also be used as a mordant in vegetable dyeing. It often highlights the green tints of the specific dyes.

Copper sulfate is used to test blood for anemia. The blood is tested by dropping it into a solution of copper sulfate of known specific gravity.

Copper sulfate...

how is metal copper extracted from its pyrite ore?

It can be extracted from copper pyrite which goes through the following step:

1. Crushing and pulverization:The big size of the ore is crushed and it is changed into a fine powder then it is taken for concentration.

2. Concentration:The obtained powder ore is concentrated by the froth floatation process. Then it is taken for roasting.

3. Roasting:It is then heated strongly in a reverberatory furnace. The volatile impurities such as sulphur, arsenic, etc are removed and pyrite ore is converted...

Write the action of it upon I)moist air II) conc. H₂SO

i. Action with moist air: After long exposure to moist air, a green layer of its basic carbonate is formed over it.

2Cu + H₂O + CO₂ + O₂ ---------------> CuCO₃.Cu(OH)₂

ii. Action of Conc. H₂SO₄: When heated with conc.H₂SO₄Sulphur dioxide gas is formed.

Cu + 2H₂SO₄-------------------> Cu(NO₃)₂ + 2NO₂ + 2H₂O

When caustic soda is added to an aqueous solution of copper sulphate, a blue precipitate of Cu(OH)2 is obtained. How will you separate Cu(OH)2 from the mixture ?

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