Topic 4: Extracting Metal and Equilibria Flashcards
What is the reactivity series?
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold
Platinum
How can you remember the reactivity series?
Pop
Stars
Can
Make
Absolute
(Carbon)
Zillions
If
Hyper
Children
Spend
Gold
Pennies
What happens as you go down the reactivity series?
Reactivity decreases
The metals become more resistant to oxidation
Harder to form cations out of the metals
What can you used to determine a metals position in the reactivity series?
Their reactions with acid and water
Displacement reactions
What are potassium’s, sodium’s and calcium reactions with water? (Top of the reactivity series)
Vigorous
Form metal hydroxide and hydrogen
What are potassium’s, sodium’s and calcium reactions with dilute acid? (Top of the reactivity series)
Explosive
Forms salt and hydrogen
What are magnesium’s and aluminiums reactions with water? (Higher middle of the reactivity series)
Reacts with the steam but not the water
Forms metal oxide and hydrogen
What are magnesium’s and aluminiums reactions with dilute acid? (Higher middle of the reactivity series)
Vigorous
Forms salt and hydrogen
What are zincs and irons reactions with water? (Lower middle of the reactivity series)
Reacts with steam but not water
Forms metal oxide and hydrogen
What are zincs and irons reactions with dilute acid? (Lower middle of the reactivity series)
Some bubbling
Forms salt and hydrogen
What are coppers, silvers, golds and platinums reactions with water? (Bottom of the reactivity series)
No reaction
What are coppers, silvers, golds and platinums reactions with dilute acid? (Bottom of the reactivity series)
No reaction
What’s a displacement reaction?
When a more reactive element takes the place of a less reactive metal in a compound
What is a redox reaction?
Where once substance in a reaction is reduced and another is oxidised
What is oxidation?
Loss of electrons
What is reduction?
Gain of electrons
How can you remember what oxidation and reduction are?
OIL RIG
Oxidation is loss Reduction is gain
What is an example of a redox reaction?
Displacement reaction
The more reactive element is oxidised and the less reactive metal is reduced
Where are most metals extracted from?
Ores from the earths crust
What metals is electrolysis used for?
Metals more reactive than carbon
(Potassium, sodium, calcium, magnesium and aluminium)
Why is electrolysis only used for these metals?
Requires a lot of energy and is expensive
Thus only used on more reactive metals as they’re harder to extract
What metals is reduction using carbon used in?
Only used to extract those metals that are less reactive than carbon
(Zinc, iron, copper, silver, gold and platinum)
What is the process of reduction using carbon?
Heating the ore with carbon to reduce it (oxygen is removed and electrons are gained)
What is extraction by electrolysis like?
Positive cations attracted to negative cathode
Gases are often formed and released from the positive anode
A molten version of the metal that is being extracted is formed below the cathode
What is the process of phytoextraction?
- Soil containing metal compounds
- Metals build up in leaves
- These are harvested then burnt - ashes contain metal compounds
- Pure metal is extracted by a displacement reaction done with a more reactive metal
What is the process of bio leaching?
- Low grade ore and a bacteria are placed into a dish - bacteria get energy from the bonds between atoms in the ore, separating out the metal in the process
- Leachate solution is added that contains metal ions
- The pure metal is then extracted by electrolysis
What are examples of biological methods of extraction?
Phytoextraction
Bio leaching
What are positives of biological methods of extraction compared to traditional ones?
Can be used to extract metals from low grade ores or waste
Less damaging to the environment
What are negatives of biological methods of extraction compared to traditional ones?
Slow
What are examples of traditional extraction methods?
Electrolysis
Reduction using carbon
What are the issues surrounding extracting metals?
Metals are non renewable resources - will run out eventually
Mining metals damages the environment
Fossil fuels need burning to provide lots of energy for extraction, causing pollution (these also are non renewable so need to be conserved)
What are benefits of recycling metals?
Reduces amount of waste sent to landfill
Reduces the need for mining - preserves finite amount of metal
Uses less energy than mining and extracting raw materials - cheaper
What are negatives of recycling metals?
May be hard to sort
What is a life cycle assessment?
An assessment of the environmental impact of a product over each stage of its life
What are the life cycle assessment stages?
- Raw materials
- Manufacturing
- Using the product
- Product disposal
What are some considerations for the raw materials stage of the life cycle assessment?
Metals need mining and extraction from ores
Raw materials for chemical manufacture often come from crude oil (non renewable resource) - combustion produces greenhouse gases
What are some considerations for the manufacturing stage of the life cycle assessment?
Uses a lot of energy and can cause pollution
Waste products need recycling or disposing of
Polluted water from manufacturing processes shouldn’t be put back into the environment
What are some considerations for the using the product stage of the life cycle assessment?
It could cause damage to the environment e.g. may release toxic fumes or greenhouses gases, or may contaminate rivers or streams
What are some considerations for the product disposal stage of the life cycle assessment?
Disposal in landfill takes up space and can cause pollution
Incineration causes air pollution
What is dynamic equilibrium?
When the froward and backward reactions are both happening at the same rate
What are reversible reactions?
Where the products can react to form the reactants again
What is the equilibrium symbol put between reactants and products?
⇌
When can equilibrium be reached?
Only reached when a reversible reaction takes place in a closed system (where nothing can enter or leave)
What happens to the equilibrium when the concentration of reactants is higher than the concentration of products?
If higher concentration of reactants than products, equilibrium lies (shifts) to the left
What happens to the equilibrium when the concentration of products is higher than the concentration of reactants?
If higher concentration of products than reactants, equilibrium lies (shifts) to the right
What happens to the concentrations of reactants and products at equilibrium?
The concentration of reactants and products don’t change
What is the Haber process?
Making ammonia out of hydrogen and nitrogen
What is the balanced Haber process equation?
N2(g) + 3H2(g) ⇌ 2NH3(g)
Why is the Haber process mainly done?
Important to make fertilisers, explosives and dyes
What are the conditions necessary for the Haber process to happen?
Temperature must be 450°C
200 atmospheres
Iron catalyst must be used
What is Le Chatelier’s Principle?
If the conditions of a reversible reaction at equilibrium are changed, the system tries to counteract that change
What happens when temperature increases in reversible reactions at equilibrium?
The equilibrium will shift to favour the ENDOTHERMIC DIRECTION TO TAKE IN HEAT ENERGY
What happens when temperature decreases in reversible reactions at equilibrium?
The equilibrium shifts to favour the EXOTHERMIC DIRECTION TO RELEASE HEAT ENERGY
What happens when pressure increases in reversible reactions at equilibrium?
The equilibrium shifts to favour the SIDE WITH FEWER MOLES OF GAS TO REDUCE PRESSURE
What happens when pressure decreases in reversible reactions at equilibrium?
The equilibrium shifts to favour the SIDE WITH MORE MOLES OF GAS TO INCREASE THE PRESSURE
What happens when concentration of reactants increases in reversible reactions at equilibrium?
The system shifts to MAKE MORE PRODUCTS
What happens when concentration of reactants decreases in reversible reactions at equilibrium?
The system shifts to MAKE MORE REACTANTS
