General Metallurgy(10.1) Flashcards
What are the physical states of metals at room temperature?
They are solids at room temperature (Exception: mercury)
Metals exist primarily in solid form, with mercury being a notable exception as it is liquid at room temperature.
In what physical states do non-metals exist?
They exist in all three states: solid, liquid, and gas
Non-metals can be found as solids (like sulfur), liquids (like bromine), and gases (like oxygen).
How do metals typically conduct heat and electricity?
They are good conductors of heat and electricity (Exception: lead)
Most metals have high electrical and thermal conductivity, with lead being a poor conductor.
What is a common property of non-metals regarding conductivity?
They are non-conductors of heat and electricity (Exception: graphite)
Graphite is a notable non-metal that can conduct electricity due to its structure.
What is the typical melting and boiling point of metals?
They have generally high melting and boiling points (Exception: alkali metals)
Alkali metals, such as lithium and sodium, have lower melting and boiling points compared to other metals.
What is a defining characteristic of non-metals in terms of melting and boiling points?
They have low melting and boiling points (Exception: diamond)
Diamond, a form of carbon, is an exception as it has an extremely high melting point.
What does it mean for metals to be malleable and ductile?
They can be beaten into thin sheets (malleable) and stretched into long wires (ductile)
Malleability and ductility are key properties that allow metals to be shaped and formed.
How do non-metals behave under stress?
They are brittle
Non-metals tend to break or shatter when subjected to stress rather than deforming.
What is the ionization energy trend between metals and non-metals?
Metals have low ionization energy, while non-metals have high ionization energy
This trend reflects the tendency of metals to lose electrons and non-metals to gain them.
What type of bond do metals generally form?
They form ionic bonds generally
Ionic bonds typically occur between metals and non-metals, where metals lose electrons.
What is the typical oxide formed by metals?
They form basic oxides usually
Basic oxides can react with acids to form salts and water.
What type of oxides do non-metals typically form?
Their oxides are acidic or neutral
Non-metal oxides can react with bases and often exhibit acidic properties.
What is the occurrence of metals in a native state?
Native or free state: Not affected by components of atmosphere like air, moisture, CO2
Metals like gold and platinum can exist in their pure form without reacting with environmental elements.
What defines a mineral?
All substances found in nature with metal in them are called minerals
Examples include various ores like cuprite and malachite.
What is an ore?
The mineral from which metal can be extracted in a commercially viable way
Ores must have high metal content and be easy to process.
What is pyrometallurgy?
The process of extracting metal by chemical reduction of ore at high temperature
Metals like iron and copper are commonly extracted using pyrometallurgy.
What is electrometallurgy?
The process of extracting metal by electrolysis of its ore in molten state
Reactive metals like sodium and potassium are extracted using this method.
What is hydrometallurgy?
The process of extracting metal by dissolving the ore in water and precipitating the metal
This method is often used for metals like silver and gold.
What is an alloy?
A homogenous mixture of metal with other metals or non-metals
Alloys often exhibit enhanced properties compared to their constituent metals.
What are ferrous alloys?
Alloys of iron with other metals or non-metals
Examples include steel and stainless steel.
What are non-ferrous alloys?
Alloys of metals other than iron
Examples include brass and bronze.
What is the significance of alloy formation?
To increase hardness, improve color, lower melting point, change reactivity, and prevent corrosion
Stainless steel is an example of an alloy that resists rust.
What are the steps in metallurgical operation?
Crushing and grinding, ore dressing, calcination, roasting, reduction of ore
Each step is crucial for effective extraction and processing of metals.
What is the froth flotation process?
A method based on preferential wetting of ore and impurities by immiscible liquids
This method is commonly used for concentrating sulphide ores.
What is calcination?
Heating concentrated ore below its melting point in absence or limited air
Calcination is used mainly for ores containing oxygen, like carbonates.
What is roasting?
Heating concentrated ore in excess air to oxidize the ore
Roasting is mainly applied to sulphide ores.
What is smelting?
Reduction of oxide ore into metal by heating with carbon at high temperature
Smelting is a key step in the extraction of many metals.
What is a flux in metallurgy?
A chemical compound added to the ore during smelting to convert refractory impurities
Flux helps in forming slag, which is easily fusible.
What is the thermite process?
A reduction process using aluminum to extract metals with high affinity for oxygen
This method is used for metals like chromium and manganese.
What initiates the reduction process in the aluminothermic process?
The heat generated by burning magnesium
This reaction is exothermic, maintaining the heat required for further reduction.
What is the general reaction in the aluminothermic process?
Metal oxide + Al → Metal + Al2O3 + heat
Examples include: Cr2O3 + Al → Cr + Al2O3 + heat.
What is electrolytic reduction?
A method for extracting reactive metals like Na, K, Mg, Ca, Al through electrolysis
It is applied when metals cannot be reduced by chemical methods due to high reactivity.
What is the process for extracting sodium in the Down’s process?
Electrolysis of molten NaCl between graphite anode and iron cathode
The reaction involves NaCl ⇄ Na+ + Cl-.
What method is used for the extraction of less reactive metals like silver and gold?
Metal precipitation
This is an example of hydrometallurgy.
What is the overall reaction for extracting silver from argentite ore?
Ag2S + NaCN → Na[Ag(CN)2] + Na2S
Followed by precipitation: Na[Ag(CN)2] + Zn → Ag + Na2[Zn(CN)4].
What types of impurities may remain after the reduction of ore?
- Other metals
- Unreduced oxide or sulphide
- Dissolved non-metals
- Residual flux, slag
These impurities vary based on the nature of the metal.
What is the distillation method based on?
Difference of boiling points between the metal and impurities
Applied for volatile or low boiling metals like Zn, Hg, Cd.
What is liquation based on?
Difference of melting points between metal and impurities
Used for purifying metals like tin and lead.
What does the poling method involve?
Stirring molten metal with poles of green wood to reduce oxides or sulfides
Used for purifying metals like copper and tin.
What is electrolytic refining?
A method where impure metal is made anode and pure metal is cathode in an aqueous solution
Metals like Cu, Zn, Pb, Ag are purified by this method.
What is zone refining used for?
Achieving high purity of metals
Impurities are more soluble in liquid metal than in solid.
Which method is used to concentrate copper pyrite?
Froth flotation
The principle is based on density difference.
What is the flux added to remove impurities in the smelting of haematite?
CaCO3
It helps remove SiO2 impurities.
What is the reducing agent used in the smelting of haematite?
CO
Carbon monoxide is used in the reduction process.
What is an example of hydrometallurgy?
Gold extraction by leaching with KCN followed by precipitation with Zn
This process involves dissolving gold in a cyanide solution.
Which property does not represent a metal?
Formation of allotropes
Metals are typically malleable, ductile, and lustrous.
What is the main characteristic of the aluminothermic process?
It is an example of pyrometallurgy
Involves high-temperature reactions.
What is a basic flux example?
CaO
Used in metal extraction processes.
Which ore is concentrated by magnetic separation?
Haematite
This method exploits the magnetic properties of the ore.
What is the process of converting zinc blende into its oxide called?
Roasting
Involves heating in excess air.
What is the purification method for zinc due to its volatility?
Distillation
This method is effective for low boiling point metals.
What is the extraction method for manganese from Mn3O4?
Aluminothermic process
Involves reduction with aluminum at high temperature.
Which metal is the most abundant in the earth’s crust?
Aluminium
It outnumbers other metals in abundance.
