Chapter 4 - Extracting Metals and Equilibria Flashcards
Reactivity series.
Potassium, Sodium, Calcium, Magnesium, Aluminum, CARBON, Zinc, Iron, HYDROGEN, Copper, Silver, Gold
Below hydrogen on series
Doesn’t react with dilute acids
Metals at the top
More easily oxidise to form cations.
Testing reactivity
Add metals to acid, perform squeaky pop test. The louder the more reactive as reaction rate is higher meaning more H2 per second.
Metal + water
(Reactive metals)
Metal + steam
(Less reactive)
Metal Hydroxide + Hydrogen
Metal Oxide + Hydrogen
Displacement reactions are examples of..
REDOX reactions.
More reactive - oxidation
Less reactive - reduced
Displacement reactions define
More reactive metals take the place of less reactive metals
Metals are found in
Ores
Aluminium ore
Bauxite Al2O3
What can be extracted using carbon?
Metals less reactive than iron can be reduced in a blast furnace.
Metals more reactive carbon must be extracted using
Electrolysis
Why electrolysis is expensive
Large amounts of electricity is expensive.
If the ore must be melted
Reduction with carbon is cheaper as carbon is cheap and fuels the heat in an exothermic reaction
Bioleaching
Uses bacteria to separate metals from ores. Bacteria carry out chemical reactions and form a leachate, contains high concentration of metals. This can be extracted using electrolysis or displacement.
Phytoextraction
Plants grown on soil with metal compounds. They are taken up and build up in tissue. They are burned forming ash with metals, extracted using electrolysis or displacement
Recycling positives
Prevents finite resources running out
Saves more energy than original extraction
Mines are damaging to environment and destroy habitat.
Reduces landfill.
Economic benefits of extraction
Extracting costs more than recycling.
Creates jobs
Life Cycle Assesment
LCA , looks at every stage of the lifetime of a product
LCA: Choice of material
Metals must be mined and extracted requiring energy, releasing pollution .
Crude oil is non-renewable and requires lots of energy in extraction
LCA: Manufacturing
Uses lots of energy
Causes pollution
Waste may be poorly disposed
Often require water, contaminated water may be let out.
LCA: Product Use
Burning fuels releases
Fertilisers can leach into water causing damage to ecosystem.
LCA: Disposal
May be disposed in Landfill, polluting land and water.
Products may be incinerated causes air pollution.
Haber process equation
N2 + 3H2 2NH3
Haber process temperature, pressure and catalyst
450C,
200 atmospheres
Iron catalyst
Dynamic equilibrium
The forward and backward reactions are happening at the same rate and time. Concentrations have reached a balance so won’t change.
Equilibrium can only be reached in a
Closed System
Equilibrium shifts right
More products (concentration) less reactant (concentration)
Equilibrium shifts left
More reactant (concentration) Less products (concentration)
What 3 things can change the position of equilibria.
Temperature,
Pressure (involving gases)
Concentrations (reactants or products)
Effect of temperature on equilibria.
Increase : Moves ENDOthermic direction.
Decrease: Moves EXOthermic direction
Le Chatelier principle
If the concentration, temperature or pressure change, the reaction will shift to COUNTERACT this.
Changing pressure on equilibria
Increasing: Moves side with few moles of GAS
Decreasing: Moves to side with more moles of GAS
Changing concentration on equilibria
Increase REACTANTS: Shifts right, to use up the added reactants.
Increase PRODUCTS: Shifts Left to use up the added products.
Decreasing has the OPPOSITE effect.
