Extraction of Crude Metals from Ores

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What is the purpose of roasting in the extraction of crude metals from concentrated ores?

To remove impurities

To reduce the metal oxides

To melt the metal

To oxidize the concentrated ore (correct)

Why is it necessary to convert the concentrated ore into oxides before reducing it to elemental metals?

To reduce the weight of the ore

To simplify the extraction process

To make the metal more magnetic

To make reduction easier (correct)

Which of the following elements is NOT removed as an impurity during roasting of sulphide ores?

Oxygen (correct)

Arsenic

Sulphur

Phosphorous

What happens to the nonmagnetic part of the ore during the extraction process?

It falls away from the magnetic region Signup and view all the answers

In which state does the metal exist in the concentrated ore before reduction?

+1 oxidation state Signup and view all the answers

Why is roasting commonly applied for converting sulphide ores into oxides?

To remove impurities and convert to oxides Signup and view all the answers

What is the basis for interpreting ΔG in metallurgical processes?

The assumption that reactants are in equilibrium with the products Signup and view all the answers

Why is the reduction of oxides of active metals by carbon considered thermodynamically not feasible?

Because the Gibbs free energy change is unfavorable Signup and view all the answers

What does a positive E0 value indicate for the electrolysis process of metal salts?

The reduction is spontaneous Signup and view all the answers

How is the Gibbs free energy change related to the electrode potential of the redox couple?

Inversely proportional Signup and view all the answers

What technique is used for extracting active metals like sodium and potassium from their ores?

Electrochemical methods Signup and view all the answers

When will a redox reaction be considered planned according to the text?

When the e.m.f of the net redox reaction is positive Signup and view all the answers

What is the product formed when borax reacts with acids?

Boric acid Signup and view all the answers

What is a use of borax mentioned in the text?

Identification of coloured metal ions Signup and view all the answers

How is boric acid prepared according to the text?

From borax and colemanite Signup and view all the answers

What is the color of boric acid as per the text?

Colorless Signup and view all the answers

What does boric acid form when reacting with sodium hydroxide?

Sodium metaborate and sodium tetraborate Signup and view all the answers

What is formed when urea fuses with B(OH)3 in an ammonia atmosphere at high temperature?

Boron nitride Signup and view all the answers

What is one advantage of using the vapour phase method for refining metals?

It prevents impurities from crystallizing along with the metal Signup and view all the answers

What is the purpose of an inert gas atmosphere in the melt method?

To prevent the oxidation of metals during purification Signup and view all the answers

Why does impurities move along with the molten zone in the melt method?

Impurities are more soluble in the solid state than in the melt Signup and view all the answers

How are elements like germanium, silicon, and gallium refined in the melt method?

By melting them in an inert gas atmosphere Signup and view all the answers

What happens to impure nickel in the Mond process for refining nickel?

It reacts with carbon monoxide to form a volatile compound Signup and view all the answers

What distinguishes the vapour phase method from the melt method in metal refining processes?

The formation of volatile compounds before decomposition Signup and view all the answers

What are the products formed when heating Potash alum to red hot?

Potassium sulphate, alumina, and sulphur trioxide Signup and view all the answers

What is the result of treating Potash alum with ammonium hydroxide?

Formation of aluminum hydroxide Signup and view all the answers

What are the uses of Alum as mentioned in the text?

Purification of water and water proofing in textiles Signup and view all the answers

Where is carbon primarily found in its native form?

Graphite Signup and view all the answers

Which element occurs as silica in sand and quartz crystal?

Silicon Signup and view all the answers