Extracting Metals and Equlibria Flashcards
What do more reactive metals do in chemical reactions?
Lose electrons to become cations
What is the relationship between metal reactivity and cation formation?
The more reactive the metal, the more easily it becomes a cation
What is the general reaction for a metal becoming a cation?
M ⟶ Mn+ + ne-
What process is described by the loss of electrons?
Oxidation
How does the position of a metal in the reactivity series affect oxidation?
The higher up the metal is in the reactivity series, the more easily it will undergo oxidation
What can be said about unreactive metals in terms of oxidation?
They are more resistant to oxidation
What does the Earth’s crust contain?
Metals and metal compounds such as gold, copper, iron oxide, and aluminium oxide
These elements are fundamental in various industrial and technological applications.
What are useful metals often combined with?
Other substances forming ores
This combination is essential for the extraction process.
What is a metal ore?
A rock that contains enough of the metal to make it worthwhile extracting
The economic viability of extracting a metal is determined by the concentration of the metal in the ore.
How must metals be extracted from their ores?
Through processes such as electrolysis, using a blast furnace, or by reacting with more reactive material
These methods depend on the type of metal and its ore.
What type of process is often involved in the extraction of metal oxides?
A reduction process since oxygen is being removed
This is crucial for metals that are found in oxide form.
What are common examples of oxide ores?
- Haematite (iron ore)
- Bauxite (aluminium ore)
These ores are significant sources of their respective metals.
What are unreactive metals?
Metals that do not have to be extracted chemically as they are often found as the uncombined element
Their stability allows them to exist in nature in a free state.
What are native metals?
Unreactive metals that do not easily react with other substances due to their chemical stability
This characteristic allows them to be found in their elemental form.
Give two examples of native metals.
- Gold
- Platinum
Both metals can be mined directly from the Earth’s crust.
What is the tendency to become oxidised linked to?
How reactive a metal is and its position on the reactivity series
Metals higher up in the reactivity series are more prone to oxidation.
How do metals higher up in the reactivity series compare to those lower down regarding oxidation?
Metals higher up are less resistant to oxidation than metals lower down
This means they oxidize more easily.
What determines the method of extraction for metals?
The position of the metal on the reactivity series
This influences whether electrolysis or reduction by carbon is used.
What extraction method is used for higher placed metals (above carbon)?
Electrolysis
These metals are too reactive to be reduced by carbon.
How can lower placed metals be extracted?
By heating with carbon
This method reduces the metals.
What is phytomining?
A process that takes advantage of how some plants absorb metals through their roots
Phytomining is used to extract metals from soil by utilizing plant biology.
Where are plants grown for phytomining?
In areas known to contain metals of interest in the soil
This location is crucial for ensuring the plants can absorb the desired metals.
How do plants absorb metals in phytomining?
Through their roots and into their vascular system
This biological process allows for the concentration of metals in specific plant parts.
Which parts of the plant are harvested in phytomining?
Shoots and leaves
These parts contain concentrated metal compounds that are useful for extraction.
What happens to the harvested plant parts in phytomining?
They are dried and burned
This process converts the biomass into ash that contains metal compounds.
What is extracted from the ash produced in phytomining?
Metal compounds
These compounds can be processed to recover useful metals.
What methods can be used to extract metals from the ash in phytomining?
Displacement reactions or electrolysis
These methods are effective for recovering metals from the ash.
What is bioleaching?
Bioleaching is a technique that makes use of bacteria to extract metals from metal ores
Bioleaching leverages biological processes for metal extraction.
Which type of bacteria is used in bioleaching?
Some strains of bacteria are capable of breaking down ores to form acidic solutions containing metal ions such as copper(II)
These bacteria facilitate the leaching process.
What is the solution called that contains metal ions in bioleaching?
The solution is called a leachate which contains significant quantities of metal ions
Leachate is crucial for the extraction process.
How can metal ions in leachate be extracted?
Metal ions can be reduced to the solid metal form and extracted by displacement reactions or electrolysis
These methods enable the recovery of metals from leachate.
What types of ores are often used in bioleaching?
Bioleaching is often used to extract metals from sulfides e.g. CuS or Fe2S
Sulfide ores are a common target for bioleaching processes.
Does bioleaching require high temperatures?
No, bioleaching does not require high temperatures
This makes bioleaching an energy-efficient method of metal extraction.
What environmental concern is associated with bioleaching?
Bioleaching produces toxic substances which need to be treated so they don’t contaminate the environment
Managing toxic byproducts is essential for environmental protection.
In addition to primary extraction, what is another use of bioleaching?
Bioleaching is also used in mining waste clean up operations
This application helps mitigate the impact of mining activities.
What process is used to manufacture ammonia?
The Haber Process
The Haber Process is a method for synthesizing ammonia from nitrogen and hydrogen gases.
What is the first stage of the Haber Process?
H2 and N2 are obtained from natural gas and the air respectively and are pumped into the compressor through pipe
Hydrogen (H2) is sourced from natural gas, while nitrogen (N2) is sourced from the air.
What happens in the second stage of the Haber Process?
The gases are compressed to about 200 atmospheres inside the compressor
High pressure is essential for the reaction to form ammonia.
What temperature is maintained in the third stage of the Haber Process?
450°C
This temperature is optimal for the catalytic reaction to occur.
What is the chemical equation for the formation of ammonia in the Haber Process?
N2 (g) + 3H2 (g) ⇌ 2NH3 (g)
This equation represents the reversible reaction between nitrogen and hydrogen to form ammonia.
What occurs in the fourth stage of the Haber Process?
Unreacted H2 and N2 and product ammonia pass into a cooling tank where ammonia is liquefied and removed
This stage involves cooling to facilitate the liquefaction of ammonia.
What happens to unreacted gases in the fifth stage of the Haber Process?
The unreacted H2 and N2 gases are recycled back into the system
Recycling unreacted gases increases efficiency and sustainability of the process.
What is one environmental impact of obtaining raw materials?
Using up limited resources such as ores and crude oil
This can lead to resource depletion.
How can obtaining raw materials damage habitats?
Through deforestation or mining
This results in loss of biodiversity and ecosystem disruption.
What is one impact of manufacturing processes on the environment?
Using up land for factories
This can lead to habitat loss and urban sprawl.
What type of machines contribute to environmental impact during production?
Fossil fuelled machines for production and transport
These machines emit greenhouse gases and contribute to air pollution.
How does the usage of a product affect the environment?
It depends on the type of product
For example, a wooden desk has very little impact, while a car has a significant impact.
What is one environmental concern regarding the disposal of outdated products?
Using up space at landfill sites
This can lead to land degradation and pollution.
What factor affects whether a product or its parts can be recycled?
The type of product
Some materials are more easily recyclable than others.
What is a life cycle assessment?
An assessment carried out using the data of a given product and the criteria of the assessment
It evaluates the environmental impacts associated with all stages of a product’s life.
Is there a perfect product with zero environmental impact?
Rarely
Most products involve a compromise between environmental impact and economical factors.
Disadvantages of recycling
Disadvantages
Collection and transport of material to be recycled requires energy and fuel
Workers, vehicles and worksites need to be organised and maintained
Materials need to be sorted before they can be recycled which also requires energy and labour
Products made from recycled materials may not always be of the same quality as the original
