Extracting Metals and Equilibrium Flashcards
What are the products when a metal reacts with cold water?
Metal hydroxide and hydrogen gas
What are the products when a metal reacts with steam?
Metal oxide and hydrogen gas
What are the products when a metal reacts with a dilute acid?
Salt and hydrogen
If a metal reacts with cold water, what does it suggest above the reactivity of this metal?
The metal is very reactive as only the most reactive can react with cold water
What does a metal reacts with oxygen but not acid or cold water suggest about the reactivity of this metal?
Not very reactive, most metals react with oxygen
What metal won’t react with water, acid or oxygen?
Gold
What is an experiment that uses displacement to compare the reactivity of two metals?
Add a solid metal to a salt solution, if the solid metal is more reactive, it will gradually disappear, displacing the metal that was in the salt solution and if nothing happens, the metal in the salt is more reactive and can’t be displaced
What would you expect to observe when magnesium is added to copper sulfate solution?
The copper sulfate solution is blue, magnesium is more reactive than copper so when magnesium is added the blue solution decolourises and copper coats the surface of the magnesium
Why can a displacement reaction be called a redox reaction?
Occurs when reeducation and oxidation are taking place, in a displacement reaction the more reactive metal atoms lose electrons to form ions and the lies reactive metal ions gain electrons to form the elements
Which metals are most easily oxidised?
Highest in the reactivity series, more likely to react with water and dilute acids to form cations
Where are most metals extracted from?
From ores found in the Earths crust
What is an ore?
A rock which contains metals often chemically combined with other substances
Which metals are found in the earths crust as uncombined elements?
Unreactive metals
What does oxidation mean?
Gain of oxygen
What does reduction mean?
Loss of oxygen
How can metals be extracted from their ores?
Reeducation with carbon: can only be done if the metal is less reactive than carbon and Electrolysis: can be done with all metals, but requires a large amount of energy
How would you extract iron from its ore?
Iron is less reactive than carbon so can be extracted by reduction with carbon and electrolysis could also be used but this would use a lot of unnecessary energy
How can aluminium be extracted from its ore?
Aluminium is more reactive than carbon so electrolysis must be used and when the molten ore undergoes electrolysis the metal forms at the cathode
When aluminium is extracted from aluminium oxide, why is it first dissolved in molten cryolite?
Aluminium oxide has a very high melting point, it’s dissolved in molten cryolite to produce an electrolyte with a lower melting point, reducing energy usage and cost
How can plants be used as an alternative metal extraction method? How does it work?
Phytoextraction: plants are grown in areas with metals in the soil, the plants take up metals through their roots and concentrate them in their shoots and leaves, these plants are burned and the metals are removed from the ash
How can bacteria be used as an alternative metal extraction method?
Bacteria extraction: some bacteria absorb metal compounds, these bacteria produce solution called leachates containing the metals and scrap iron can be used to remove the metal from the leachate
What are limitations of biological methods of extraction?
Only suitable for low grade ores with smaller quantities of metals, slow processes and require displacement or electrolysis for the final step
How is a metals relative resistance to oxidation related to its position in the reactivity series?
Metals lower in the reactivity series are less reactive, this means they are less likely to form their cations so are more resistant to oxidation
What are the advantages of recycling metals?
Economically beneficial, less wage produced so less landfill, less energy is required, more sustainable and recycling process provides employment
What is a life cycle assessment?
Analysis of the overall environmental impact that a product may have throughout its lifetime
What different factor does a life cycle assessment of a product consider?
Extraction and processing of raw materials, manufacturing, packaging and transportation, use of the product and disposal
What is a reversible reaction?
A reaction in which the products can react to torn the original reactants
How can the direction of a reversible reaction be altered?
Changing the reaction conditions
What is meant by the term dynamic equilibrium?
The rate of the forward reaction equals the rate of the backwards reaction, this means the concentration of reactants and products are constant even though compounds are continually reacting
What is a closed system?
A system where nothing is added or removed, all reactants and products remain in the reaction vessel
Why is equilibrium only reached if the reaction takes place in a closed system?
The closed system prevents any reactants and products escaping so that they are able to react continuously
What is the Hager process?
An industrial process used to produce ammonia
Where are the sources of nitrogen and hydrogen for the Huber process?
Nitrogen: extracted from the air and Hydrogen: obtained from natural gas
What conditions are used for the Habor process?
450C temperature, 200 atm pressure and iron catalysts
What is the effect of increasing the temperature of a reversible reaction if the forward reaction is endothermic?
The towards reaction is endothermic so increasing the temperature favours the forwards reaction, the equilibrium will shift towards the forward reaction and the yield of the product
What is the effect of changing the pressure of a reversible gaseous reaction?
An increase in pressure will favour the reaction that produces the least number of molecules, the equilibrium positions will shift towards the side that produces the fewest gaseous molecules
What is the effect of increasing the pressure in the yield of ammonia in the Haber produces?
Increasing the pressure will shift equilibrium to the right as there are fewer molecules of gas, the yield of ammonia will increase
What effect does the concentration of the reactants are increased during a reversible reaction on the equilibrium position?
The equilibrium will shift to the right so the product yield will increase, this will reduce the effect of the increased concentration of the reactants
