TOPIC 4- EXTRACTING METALS AND EQUILIBRIA Flashcards
Micrometers in standard form
10^-6
Nanometers in standard form
10^-9
How big are nano particles
Range from 1-100nm and only contain a few hundred atoms
Why are nano particles used as catalysts?
Because they have large surface area in comparison to their volume
Example of a nanoparticle
Zinc oxide is used as sunscreen as it absorbs UV radiation while remaining transparent.
Advantages of nanoparticles
High surface area to volume ratio, catalytic
Disadvantages of nanoparticles
Long term effects are unknown, can enter our living cells, bad for environment
Metals reaction with acids tell you what about them
Their level of reactivity
Metal + acid»_space; ?
Salt + hydrogen
How does the reactivity affect the speed of the reaction
The more reactive the metal, the quicker the rate of reaction
How do you confirm hydrogen is released?
Squeaky pop test
Mg + 2HCl» ?
MgCl2 + H2
How do you speed up the rate of reaction ?
Heat or catalyst
Which metals react with water
K, Na, Li, Ca
Metal + water»_space; ?
Metal hydroxide + hydrogenk
Metal + steam»?
Metal oxide + hydrogen
Reactivity series in order from top
K, Na, Ca, Mg, Al, C, Zn, Fe, Sn, Pb, H, Cu, Ag, Au
What’s a redox reaction?
A reaction in which oxidation and reduction ocurr
How does the reactivity of a metal affect the temp in displacement
More reactive = more heat released
Define displacement
When a more reactive metal displaces a less reactive metal from its compound
Oxidation involving oxygen
When a substance gains oxygen
Reduction involving oxygen
When a substance loses oxygen
Oxidation with electrons
Loss of electrons
Reduction involving electrons
Gain of electrons
Half equation of each from: Mg + CuSO4> MgSO4 + Cu
Mg > Mg^2+ + 2e-
Cu^2+2e-> Cu
Oxidising agent
Accepts electrons and gets reduced
Reducing agent
Donates electrons and gets oxidised
Metal ore
A rock containing enough metal out of its compounds to make it economically viable to extract.
Ores vs the actual metal
They hav different properties
Mercury ore
Cinnabar
Aluminium ore
Bauxite
How does a metals reactivity affect its ease of extraction
The more reactive = the harder to extract
How do you extract metals below carbon in the reactivity series
Reduction with carbon
How do you extract metals above carbon in the reactivity series?
Electrolysis
Metal oxide + carbon >?
metal + carbon dioxide
Biological ways to extract low grade ores?
Bio leaching and phytomining
What’s phytomining?
Planting crops in copper rich soil so that they absorb it through their roots. Plants are burnt to produce copper ash
Advantages of phytomining
Carbon neutral
Disadvantages of phytomining
Produces impure copper
What’s bio leaching?
Bacteria that can absorb metal compounds to produce leachates that contain copper compounds.
Disadvantages of bioleaching
V slow
Why would (expensive) cryolite be mixed in with the compound before electrolysis.
To lower its mp
Electrolysis
Breaking down of a substance using electricity
Electrolyte
Molten or dissolved ionic compound
Anode charge
Positive
Cathode charge
Negative
Flow of electrons
Anode to cathode
What’s attracted to cathodes and what charge
Cations (positive)
What’s attracted to anodes and what charge
Anions (negative)
What happens when the cations reach the cathode?
They are reduced (gain electrons) and discharged.
When anions move to the anode, what do they do?
They are oxidised (lose electrons) and so are discharged
Ionic compound
Compound with a positive and negative ion formed in a lattice shape
What electrons are used in electrolysis of molten ionic compounds?
Inert (unreactive) like lead for example
What ions are included in electrolysis of aqueous solutions
H+, OH- and ionic compound
What happens at the cathode in electrolysis of aqueous solutions?
If the metal is more reactive than hydrogen, hydrogen is produced. If the metal is less reactive than hydrogen, the metal is produced.
What happens at the anode in electrolysis of aqueous solutions?
If a halide is present, the halide is produced. If there’s no halide present, oxygen and water is produced.
What’s corrosion
The rusting of a metal. (The reaction of metal and oxygen)
What do you need to corrode a metal?
Oxygen and water
Metal + water + oxygen >?
Hydrated metal oxide
How do you prevent corrosion
Coat it in a barrier (tarnish) or put a more reactive metal with it (metal coating)
In purification if copper what’s the cathode made out of?
Pure copper
In purification of copper, what’s the anode made out of?
Impure copper
In purification of copper, what’s the electrolyte ?
Copper sulfate
What’s the voltage directly proportionate to in purification of copper?
The mass of the cathode due to quicker donation and loss of electrons.
What does the cathode do in purification of copper ?
It grows heavier due to reduction of copper ions leading to discharged atoms deposited on the cathode.
What does the anode do during copper purification?
It grows lighter due to oxidisation of the impure copper molecules causing more copper to dissolve into the solution. The impurities are left as a slush at the bottom.
Why do people keep pushing recycling of metals?
Because metal extraction is time consuming, expensive and harmful to the environment. Also forms of disposal are also very harmful to the environment.
Advantages of recycling metals
Lower energy consumption/cost, saving of resources, less waste/pollutants and creation of jobs
Disadvantages of recycling metals
Alloys are hard to recycle, transport cost/emissions, sorting, impurity of end product, and money cost to sort and collect
What does the lifecycle assessment cover?
Extraction > manufacturing > use > disposal
Landfill disadvantages
Takes up space, pollutes surroundings, doesn’t preserve materials
Dynamic equilibrium
When the forwards and backwards reactions occur at the same rate, meaning concentrations of reactants and products won’t change
What type of system do dynamic equilibriums take place in?
Closed
Closed systems
A system in which no reactants/ products can escape.
Equilibrium lying to the right
Concentration of products is greater than that of reactants.
Equilibrium lying to the left
Concentration of reactants is greater than that of products
Le Chatelier’s principle
If there’s a change in concentration, temperature or pressure in a reversible reaction, the equilibrium will move to counteract that change.
What happens when you decrease the temperature of a reaction in equilibrium?
The equilibrium will shift to the exothermic direction to produce more heat.
What happens when you increase the temp of a reaction in equilibrium?
The equation Librium shifts to the endothermic direction to take in heat and therefore decrease temp.
What happens when you increase the pressure of a reaction in equilibrium?
The equilibrium will shift to side w fewer moles to reduce pressure
What happens when you decrease the pressure of a reaction in equilibrium?
The equilibrium will shift to the side with more moles of gas to increase pressure.
What happens when you increase concentration of reactants?
The equilibrium will shift to the right to produce more products.
What happens when you increase concentration of products?
The equilibrium will shift to the left to produce more reactants.
