Cuprous oxide formed during roasting of cuprous sulphide is mixed with few amount of cuprous sulphide and heated in a reverberatory furnace to get metallic copper.
$$2C{u_2}O + C{u_2}S \to 6Cu + S{O_2}$$
62.
Aluminium is extracted from alumina $$\left( {A{l_2}{O_3}} \right)$$ by electrolysis of a molten mixture of
Fused alumina $$\left( {A{l_2}{O_3}} \right)$$ is a bad conductor of electricity. Therefore, cryolite $$\left( {N{a_3}Al{F_6}} \right)$$ and fluorspar $$\left( {Ca{F_2}} \right)$$ are added to purified alumina which not only make alumina a good conductor of electricity but also reduce the melting point of the mixture to around $$1140\,K.$$
63.
In Goldschmidt aluminothermic process which of the following reducing agents is used :
Reduction by powdered aluminium is known as Gold-Schmidt aluminothermic process. This process is employed in cases where metals have very high $$m.p.$$ and are to be extracted from their oxides.
64.
The impurities associated with mineral used in metallurgy are called collectively?
Impurities associated with minerals are called gangue or matrix.
65.
Sulphide ores of metals are usually concentrated by froth floatation process. Which one of the following sulphide ores offers an exception and is concentrated by chemical leaching?
Galena $$(PbS),$$ copper pyrites $$\left( {CuFe{S_2}} \right)$$ and argentite $$\left( {A{g_2}S} \right)$$ are are concentrated by froth floatation process but sphalerite $$\left( {ZnS} \right)$$ is concentrated by chemical leaching.
66.
Which one of the following ores is best concentrated by froth floatation method?
No explanation is given for this question. Let's discuss the answer together.
69.
Which method of purification is represented by the following equation?
\[Ti\left( s \right)+2{{I}_{2}}\left( g \right)\xrightarrow{523K}Ti{{I}_{4}}\left( g \right)\] \[\xrightarrow{1700K}Ti\left( s \right)+2{{I}_{2}}\left( g \right)\]
Van Arkel is a method in which heat treatment is used to purify metal in this process metals are converted into other metal compound for loosly coupled like as iodine to make metal iodide which are easily decomposed and give pure metal. The process is known as Van Arkel method.
70.
Impurities of sulphur, silicon and phosphorus can be removed from cast iron by adding
A
carbon which reduces the impurities
B
water which dissolves the impurities
C
limestone which changes impurities into oxides and pass into slag
D
iron oxide which reacts with impurities by forming slag
Answer :
limestone which changes impurities into oxides and pass into slag