Extraction of Metals Quiz

Questions and Answers

Which method is primarily used to extract highly reactive metals from their ores?

Thermal decomposition

Reduction with coke

Self-reduction

Electrolysis (correct)

What term describes the undesirable impurities found in ore?

Concentration

Ore

Matrix

Gangue (correct)

Which metals are typically extracted through the self-reduction method?

Iron and Lead

Copper and Mercury (correct)

Silver and Gold

Zinc and Calcium

What is the primary reason why extracting highly reactive metals cannot be achieved through heating with carbon?

They react with carbon to form stable compounds. Signup and view all the answers

What does metallurgy refer to in the context of metal extraction?

The extraction and refining of metals. Signup and view all the answers

Which of the following is not a method used for metal extraction based on reactivity?

Chemical precipitation Signup and view all the answers

Which of the following elements is considered very less reactive and found in a metallic state in nature?

Gold Signup and view all the answers

What is the process called when gangue is removed from ore?

Enrichment Signup and view all the answers

Which method involves igniting a mixture to obtain pure metals?

Gold-Schmidt aluminothermic reduction Signup and view all the answers

What type of metals are typically reduced using electrolytic methods?

Highly reactive metals Signup and view all the answers

During the electrolytic refining process, the impure metal serves as the _____?

Anode Signup and view all the answers

What is the product formed at the cathode during the electrolysis of sodium chloride?

Sodium Signup and view all the answers

Which of the following is NOT a common impurity typically removed in the refining of metals?

Electrolyte solution Signup and view all the answers

What is the role of the ignition mixture in the thermite reaction?

To initiate the reaction Signup and view all the answers

What by-product is typically formed from the reaction of iron(III) oxide and aluminum?

Aluminum oxide Signup and view all the answers

What type of oxide is formed when non-metals react with oxygen?

Acidic oxides Signup and view all the answers

What occurs to impurities during the electrolytic reduction process?

They settle as anode mud Signup and view all the answers

What phenomenon explains why calcium floats when formed in the presence of water?

Hydrogen gas bubbles adhere to calcium's surface Signup and view all the answers

Which of the following is a non-lustrous metal?

Sodium Signup and view all the answers

Which of the following metals will not displace copper from a solution of its salts?

Silver Signup and view all the answers

What is the green substance formed on a copper plate exposed to air for a week?

Basic copper carbonate Signup and view all the answers

What is the primary reason sodium chloride conducts electricity only in molten or aqueous states?

Movement of ions Signup and view all the answers

Which process involves depositing metal onto a surface using electric current?

Electroplating Signup and view all the answers

What compound is formed by the reaction of iron with steam over prolonged exposure?

Iron (II,III) oxide Signup and view all the answers

Which element reacts with oxygen to form a compound that has a high melting point and is soluble in water?

Calcium Signup and view all the answers

What is a common example of an alloy that consists of copper and zinc?

Brass Signup and view all the answers

What happens to metal ions at the cathode during electrolysis?

They are reduced to pure metal. Signup and view all the answers

Which method prevents corrosion by forming a protective layer of zinc?

Galvanization Signup and view all the answers

Why do alloys generally exhibit increased resistance to corrosion?

The mixture of metals alters their chemical properties. Signup and view all the answers

What is the primary function of sacrificial protection in preventing corrosion?

To corrode instead of the protected metal. Signup and view all the answers

What is the outcome when calcium is added to water?

It floats on the surface. Signup and view all the answers

What is the result of oxidation at the anode during electrolysis?

The release of electrons. Signup and view all the answers

Which property is NOT true for sulphur as a non-metal?

It can undergo malleability. Signup and view all the answers

What explains the acidic nature of magnesium oxide?

It forms magnesium hydroxide with water. Signup and view all the answers

What characteristic of ionic compounds is highlighted by their ability to conduct electricity?

They dissociate into ions in molten or aqueous forms. Signup and view all the answers

Why are sodium and potassium metals stored under kerosene?

To prevent oxidation from air. Signup and view all the answers

Which statement correctly describes aluminium oxide?

It is amphoteric due to reactions with acids and bases. Signup and view all the answers

What happens to a blue copper sulphate solution when an iron strip is introduced?

It turns pale green due to formation of iron sulphate. Signup and view all the answers

What indicates that magnesium is a metal based on its properties?

It is a good conductor of heat and electricity. Signup and view all the answers

Which of the following accurately reflects the behavior of compounds formed by metals and non-metals?

They typically form ionic compounds. Signup and view all the answers

Study Notes

Occurrence of Metals

Earth's crust is the primary source of metals; seawater contains soluble salts.
Minerals are naturally occurring elements or compounds, while ores are minerals from which metals can be profitably extracted.

Extraction of Metals from Ores

Metallurgy refers to the extraction and refinement of metals from ores.
Extraction techniques depend on metals' reactivity:
- Highly Reactive Metals: Extracted via electrolysis due to strong bonds with ore components (e.g., Potassium, Sodium, Calcium, Magnesium).
- Moderately Reactive Metals: Extracted using the reduction process with agents like coke (e.g., Zinc, Iron, Lead).
- Less Reactive Metals: Extracted through self-reduction by heating (e.g., Copper, Mercury).
- Very Less Reactive Metals: Found in free metallic state (e.g., Silver, Gold, Platinum).

Concentration of Ores

Gangue (undesirable impurities) must be removed to enrich ores.
Low reactivity metals undergo self-reduction with heat, allowing the conversion of sulfide ores to oxides.

Methods of Metal Extraction

Thermite Reaction: A mix of concentrated oxide ore and aluminum reduces metal oxide to metal (e.g., Chromium and Iron).
Electrolytic Reduction: Reactive metals (e.g., Na, K, Mg) are reduced from molten oxides or hydroxides using electric current.

Refining/Purification of Metal

Impurities removed during refining include unreacted ore, byproducts, and non-metals.
Electrolytic Refining of Copper:
- Uses impure copper as anode and pure copper as cathode; metal ions reduce on cathode.

Corrosion

Gradual deterioration of metals due to moisture, air, or chemicals (e.g., rusting of iron).

Prevention of Corrosion

Coating: Paint, oil, or grease prevents moisture and air contact.
Alloying: Alloys exhibit enhanced resistance; e.g., stainless steel.
Galvanization: Coating iron with zinc for protection from corrosion.
Electroplating: Coating one metal with another using electric current.
Sacrificial Protection: Mg prevents iron corrosion by undergoing oxidation instead.

Alloys

Homogeneous mixtures of metals or non-metals enhance properties like hardness and strength (e.g., Brass = Copper + Zinc, Bronze = Copper + Tin).

Previous Year Questions

Questions include arrangements of metals by reactivity, valency details, reactions with water, and features of ionic compounds.
Responses involve reasoning about properties of metals vs. non-metals, stimulus for alloy formation, and behaviors within chemical reactions.

Key Points on Ionic Compounds

Formed by the transfer of electrons from metals to non-metals.
General properties include high melting points, solubility in water, and conductivity in molten and aqueous forms.

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Description

Test your knowledge on the occurrence of metals in Earth's crust and the extraction processes involved in metallurgy. This quiz covers essential concepts such as minerals, ores, and refining techniques used to obtain pure metals. Perfect for students studying materials science or geology.