gcse chemistry c14 retrieval practice

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What is a finite source?

A natural resource that is limited in supply and can run out.

Give 4 examples of a finite source

-metal ores
-crude oil
-limestone
-coal

What is a renewable source?

A natural resource that can be replenished naturally over time and won't run out.

Give 2 examples of a renewable source

-Solar Energy
-Wind Energy

How are solid particles removed from reservoir water?

Filtration- water passes through layers of sand, gravel, and other materials that trap solid particles.

Why is chlorine often added to drinking water?

To kill harmful bacteria and other pathogens, making the water safe to drink.

What is desalination?

The process of removing salt and other impurities from seawater to make it safe to drink.

What is potable water?

Water that is safe to drink, contains dissolved substances

Describe the 4 steps used in sewage treatment:

-Water passed through screen, catching large objects (eg leaves, twigs)
-Aluminium sulfate and lime added to water. Dirt clumps together, sinks to bottom of tank and forms sludge.
-Water passed through filter made of sand and gravel, removing remaining mud/grit particles
-Water is disinfected with chlorine/UV light/ozone to remove remaining contaminants and pathogens.

Describe what happens to the sludge from the primary treatment

It is treated further through processes like anaerobic digestion to produce biogas and can be used as fertiliser. If it can't be safely recycled or used, it may be sent to a landfill.

What is the definition of a metal ore?

A naturally occurring rock that contains a sufficient concentration of a metal/metal compound.

Metal ores are mined mostly in open cast mines. Suggest 2 environmental effects of mining.

-can destroy large areas of natural habitats, leading to biodiversity loss
-contamination of soil and water sources with toxic chemicals and heavy metals.

Metal ores are mined mostly in open cast mines. Suggest 2 economic effects of mining.

-creates jobs, boosting local and national economies by providing employment opportunities.

• Mining brings in money by extracting and selling valuable metals, benefiting governments and businesses.

One of the main methods for extracting copper form copper rich ores is to react copper oxide from the ore with sulphuric acid. Write a word equation for this reaction.

Copper oxide + Sulphuric acid → Copper sulfate + Water

Scrap iron is then added to the solution formed by the reaction to form copper. Write a word equation for this reaction. What type of reaction is this?

• Iron + Copper sulfate → Iron sulfate + Copper
• This is a displacement reaction, where iron displaces copper from the copper sulfate solution because iron is more reactive than copper.

Explain why gold would not be able to be used in the place of iron in the reaction in question 15.

Gold is less reactive than copper, so it cannot displace it in a reaction.

Give an environmental reason why scrap iron is used

Scrap iron helps recycle materials and reduces the need to mine new iron, which is better for the environment.

Give an economic reason why scrap iron is used

Using scrap iron is cost-effective because it is cheaper than mining and processing new iron ore.

Describe how copper can be extracted from copper rich ores by smelting

Copper ore is heated in a furnace to a high temperature. The heat causes the copper to separate from the ore, forming molten copper, which is then collected and cooled to produce pure copper metal.

Suggest 2 environmental problems associated with smelting

• Releases harmful gases like SO₂, causing acid rain and health issues.
• Can release heavy metals and toxins, leading to soil and water pollution.

Describe how copper can be purified using electrolysis. You should include a diagram in your answer.

Anode: Impure copper (copper and other metals).
Cathode: Pure copper sheet.
Electrolyte: Copper sulfate solution (CuSO₄).
Process:
At the Anode: Impure copper dissolves into the solution, releasing Cu²⁺ ions.
In the Solution: Cu²⁺ ions move towards the cathode.
At the Cathode: Cu²⁺ ions gain electrons and deposit as pure copper.

Write half equations for the oxidation and reduction reactions happening at the electrodes

At the Anode (Oxidation):
Cu (s) → Cu2+(aq) + 2e−
At the Cathode (Reduction):
Cu2+(aq) + 2e− → Cu(s)

Suggest 2 environmental problems with purifying copper by electrolysis

Energy Consumption: The process requires a lot of electricity which could lead to CO₂ emissions if sourced from non-renewable energy.
Chemical Waste: H₂SO₄ and CuSO₄ can cause soil and water pollution.

Suggest an economic problem with purifying copper by electrolysis

The process is costly due to high energy consumption and the need for expensive equipment.

What is the difference between a "copper rich ore" and a "low grade copper ore"?

Copper-Rich Ore: Higher % of Cu, easier and cheaper to process.
Low-Grade Copper Ore: Lower % of Cu, harder and more expensive to process.

Why are the methods used for extracting copper from a low grade ore different to the methods used to extract copper from a high grade ore?

Different methods are used to make extraction cost-effective and economical based on the copper content and required processing.

Describe the main steps involved in extracting copper from a low grade ore by phytomining

-In the low-grade copper ore area, plants absorb copper from the soil.
-Collect and burn the plants to produce ash.
-Dissolve (leach) copper from the ash using H₂SO₄, producing a leachate of CuSO₄.
-Extract copper from the CuSO₄ solution using electrolysis and a displacement reaction with iron.

Suggest 2 advantages and 2 disadvantages of phytomining

Advantages:
-reduces need for traditional mining, which can be damaging to the environment.
-can be used to clean up polluted soils by extracting metals.
Disadvantages:
-it takes longer than traditional mining methods because plants need time to grow.
-amount of copper extracted is often less compared to conventional mining, making it less efficient on a large scale.

Describe how bioleaching is used to extract copper from a low grade ore

-Special bacteria are introduced to the low-grade copper ore. These bacteria feed on the ore, breaking it down and releasing copper ions into solution.
-As the bacteria work, a solution called leachate is formed, which contains Cu²⁺ ions.
The Cu²⁺ ions in the leachate are then extracted using either electrolysis or a displacement reaction with iron, producing pure copper.

Suggest an advantage and disadvantages of bioleaching

Advantage- less harmful to the environment compared to traditional mining, as it doesn't require the use of harmful chemicals and reduces energy consumption.
Disadvantage-can take several months to years to extract copper, making it a much slower method compared to traditional mining techniques.

Why are life cycle assessments (LCAs) conducted?

LCAs evaluate the environmental impact of a product from creation to disposal to help make more sustainable choices.

What are the main steps in a LCA?

Define Goals: Set purpose and range.
Inventory Analysis: Gather data on inputs and outputs.
Impact Assessment: Evaluate environmental impacts.
Interpretation: Analyse and use the results for decision-making.

What factors are considered for each stage of a LCA?

-Raw Material Extraction: How resources are gathered and their environmental effects.
-Manufacturing: Energy use, emissions, and waste from making the product.
-Distribution: Environmental impact of transporting the product.
-Usage: Resources and energy used while the product is in use.
-End of Life: How the product is disposed of, recycled, and its environmental impact.

What are the 3 aims of the reduce, reuse, and recycle campaign?

reduce: minimise waste and resource use.
reuse: extend the life of products and materials.
recycle: reduce landfill waste.

Explain the main stages in recycling a metal

• Gather scrap metal from various sources like recycling bins.
• Separate different types of metals and remove non-metals.
• Cut/shred the metal into smaller pieces to make it easier to process.
• Heat the shredded metal in a furnace to melt it down into a liquid form.
• Remove impurities from the molten metal to ensure high quality.
• Pour the purified molten metal into moulds to form new metal products or ingots.
• Supply the recycled metal products to manufacturers for use in new products.

What are the difficulties when recycling copper?

Hard to separate from other materials.
Requires significant energy.
Can be costly compared to extracting new copper.

What is sustainable development?

Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs