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Questions and Answers
Which metal reacts the most vigorously with dilute hydrochloric acid?
Which metal reacts the most vigorously with dilute hydrochloric acid?
- Aluminium
- Magnesium (correct)
- Zinc
- Iron
What gas is liberated when metals react with dilute hydrochloric acid?
What gas is liberated when metals react with dilute hydrochloric acid?
- Hydrogen (correct)
- Carbon dioxide
- Nitrogen
- Oxygen
Which metal forms nitrate salts when reacting with nitric acid?
Which metal forms nitrate salts when reacting with nitric acid?
- Zinc
- Iron
- Copper (correct)
- Aluminium
What can dissolve noble metals like gold and platinum?
What can dissolve noble metals like gold and platinum?
Which metal is commonly used in Aqua Regia preparation?
Which metal is commonly used in Aqua Regia preparation?
What is formed when iron reacts with hydrochloric acid?
What is formed when iron reacts with hydrochloric acid?
What process is used to transform sulphide ores into oxides for easier metal extraction?
What process is used to transform sulphide ores into oxides for easier metal extraction?
Which of the following metals is NOT moderately reactive and thus used as a reducing agent for metal extraction?
Which of the following metals is NOT moderately reactive and thus used as a reducing agent for metal extraction?
In the reaction 3Mn + 2Al2O3 + heat -> 3 MnO2 + 4 Al, which substance undergoes oxidation?
In the reaction 3Mn + 2Al2O3 + heat -> 3 MnO2 + 4 Al, which substance undergoes oxidation?
What is the purpose of calcination in metal extraction?
What is the purpose of calcination in metal extraction?
Which metal is reduced by carbon in the extraction process discussed?
Which metal is reduced by carbon in the extraction process discussed?
Why are metals like sodium, calcium, and aluminium used as reducing agents in metal extraction?
Why are metals like sodium, calcium, and aluminium used as reducing agents in metal extraction?
What is the main principle behind the hydraulic separation method described in the text?
What is the main principle behind the hydraulic separation method described in the text?
In the Wilfley table method, why are the heavier particles collected on the slits between wooden riffles?
In the Wilfley table method, why are the heavier particles collected on the slits between wooden riffles?
What is the function of the forceful jet of water introduced in the hydraulic separation method tank?
What is the function of the forceful jet of water introduced in the hydraulic separation method tank?
What equipment is required for the Magnetic Separation Method mentioned in the text?
What equipment is required for the Magnetic Separation Method mentioned in the text?
Why are gangue particles carried away with flowing water in the Wilfley table method?
Why are gangue particles carried away with flowing water in the Wilfley table method?
How does the hydraulic separation method differentiate particles?
How does the hydraulic separation method differentiate particles?
What is the purpose of calcining the precipitate of Al(OH)3 obtained in Bayer's and Hall's processes?
What is the purpose of calcining the precipitate of Al(OH)3 obtained in Bayer's and Hall's processes?
In the electrolytic reduction of alumina, what is the function of the graphite lining in the steel tank?
In the electrolytic reduction of alumina, what is the function of the graphite lining in the steel tank?
What role does cryolite (Na3AlF6) play in the extraction of aluminium?
What role does cryolite (Na3AlF6) play in the extraction of aluminium?
What happens to the anodes during the electrolysis of alumina?
What happens to the anodes during the electrolysis of alumina?
Why is molten aluminium collected at the bottom of the steel tank during electrolytic reduction?
Why is molten aluminium collected at the bottom of the steel tank during electrolytic reduction?
Which gas is liberated at the anode during the electrolysis of alumina?
Which gas is liberated at the anode during the electrolysis of alumina?
What is the purpose of concentration of ores in metallurgy?
What is the purpose of concentration of ores in metallurgy?
Which method is used for separating heavy particles of ores from light particles of gangue based on gravitation?
Which method is used for separating heavy particles of ores from light particles of gangue based on gravitation?
What is the function of the Wilfley table in the concentration of ores?
What is the function of the Wilfley table in the concentration of ores?
Why is the concentration of ores important in metallurgy processes?
Why is the concentration of ores important in metallurgy processes?
What determines the exact method to be used for concentrating ores in metallurgy?
What determines the exact method to be used for concentrating ores in metallurgy?
In the concentration of ores, why is separation based on gravitation effective?
In the concentration of ores, why is separation based on gravitation effective?
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Study Notes
Reaction of Metals with Acids
- When metals (Al, Mg, Zn, Fe) react with dilute sulphuric acid or hydrogen chloride, salt and hydrogen gas are formed.
- The reactivity of these metals can be indicated by the following sequence: Mg > Al > Zn > Fe
- Examples of reactions:
- Mg(s) + 2HCl (aq) → MgCl2(aq) + H2(g)
- 2Al (s) + 6HCl (aq) → 2AlCl3(aq) + 3H2(g)
- Fe(s) + 2HCl (aq) → FeCl2(aq) + H2(g)
- Zn (s) + HCl (aq) → ZnCl2(aq) + H2(g)
Reaction of Metals with Nitric Acid
- Nitrate salts of metals are formed when metals react with nitric acid.
- Various oxides of nitrogen (N2O, NO, NO2) are also formed in accordance with the concentration of nitric acid.
- Examples of reactions:
- Cu(s) + 4 HNO3 (aq) (Concentrated) → Cu(NO3)2(aq) + 2NO2(g) + 2H2O (l)
- Cu(s) + 8HNO3 (aq) (Dilute) → Cu(NO3)2(aq) + 2NO(g) + 4H2O (l)
Reaction of Metals with Salts of Other Metals
- Metals can be extracted in pure form and then purified by different methods of purification.
- This entire process is called metallurgy.
Basic Principles of Metallurgy
- Pure metal is obtained from the ore by the following stages:
- Concentration of ores
- Separation of gangue from the ore
- Purification of the metal
- Various ways are used for concentration of ores, depending on the physical properties of the metal and the gangue.
- Examples of methods for concentration of ores:
- Separation based on gravitation
- Magnetic separation
- Hydraulic separation method
Extraction of Aluminium
- Alumina is extracted from the ore by the following steps:
- Concentration of ores
- Separation of gangue from the ore
- Purification of alumina
- Alumina is then reduced to aluminium by electrolysis.
- The electrolysis is done in a steel tank with a graphite lining.
- The electrode reactions are:
- Anode reaction: 2O2 → O2 + 4e-
- Cathode reaction: Al3+ + 3e- → Al
Extraction of Moderately Reactive Metals
- Moderately reactive metals such as iron, zinc, lead, and copper occur in nature as sulphide salts or carbonates.
- These metals are obtained by roasting or calcination of their ores.
- Roasting: 2ZnS + 3O2 → 2ZnO + 2SO2
- Calcination: ZnCO3 → ZnO + CO2
- The metal oxide is then reduced to the metal by using a suitable reductant such as carbon.
- Example: ZnO + C → Zn + CO
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