Topic 4 - Extracting Metals and Equilbria✅

lowk this topic aint even diabolical

Deduce the relative reactivity of some metals, by their reactions with water, acids and salt solutions

• Most reactive - react with water

• (metal + water = metal hydroxide + hydrogen)

• Reactive - react with acid

• (metal + acid = salt + hydrogen)

• Least reactive - react with oxygen

• (metal + oxygen = metal oxide)

Explain the displacement reactions as redox reactions

• More reactive metals form cations, since they displace the less reactive metal. This means they lose an electron and therefore are oxidised

• Less reactive metals form atoms as they are displaced. They gain electrons and are reduced.

Mnemonic for reactivity series

• Pole

• sitters

• cruise

• madly

• around

• circuits,

• zipping

• in

• hairpin

• curves,

• speeding

• gracefully.

Explain the reactivity series of metals

• Potassium is most reactive

• Sodium

• Calcium

• Magnesium

• Aluminium

• Carbon

• Zinc

• Iron

• Hydrogen

• Copper

• Silver

• Gold is least reactive

Where are most metals found

Extracted from ores in the Earth's crust

Where are unreactive metals found

In the Earth's crust as the un combined elements

What is oxidation and what is reduction

Oxidation

• loss of electrons

• gain of oxygen

Reduction

• gain of electrons

• loss of oxygen

What does the extraction of metals involve

• Reduction of ores

• Metals less reactive than carbon can be extracted from their oxides by reduction to remove the oxygen and therefore obtain the pure metals

Explain why the method used to extract a metal from its ore is related to its position in the reactivity series

• Metals can only be extracted by 'reduction of carbon' is the metal is less reactive than carbon

• If it is more reaction than carbon, electrolysis may be used

• Iron is extracted by heating with carbon

• Aluminium is extracted by electrolysis

Pros and cons of bioleaching.

• pros = does not require high temperatures,

• cons = slow, toxic substances and sulfuric acid can be produced which damages the environment

Pros and cons of phytoextraction

• pros = can extract metals from contaminated soils, does not produce harmful gases

• cons = more expensive than mining some ores, dependent on weather conditions

Explain how a metal's relative resistance to oxidation is related to its position in the reactivity series

• Relative resistance to oxidation is the same as relative resistance to losing electrons

• The less reactive a metal is, the more resistant it is to oxidation

• This is because, for a metal to react, it forms a positive ion via oxidation

What are the advantages of recycling metals

• Recycling is good because it requires less energy to melt and remould metals than it does to extract new metals from their ores

• Mining ores produces noise pollution and dust

• Recycling allows for waste metals to be reused. This saves money and means the supply of raw materials will last longer

What does the life cycle assessment for a product involve

The consideration of the effect on the environment of:

• obtaining the raw materials,

• manufacturing the product, using the product

• and disposing of the product

What is a reversible reaction

• In some chemical reactions, the products of the reaction can react to produce the original reactants

• This is a reversible reaction

How can a reverse reaction be achieved

• The direction of the reaction can be changed by changing the conditions

• E.g. if the forwards reaction takes place in hot conditions, lowering the temperature can allow the reverse reaction to take place

Symbol for reversible reaction

⇌ or É

What is meant by dynamic equilibrium

• A dynamic equilibrium is one in which the rate of the forward reaction equals the rate of the reverse reaction

• and the concentrations of the reactants and products remain constant

Describe the formation of ammonia

• A reversible reaction between nitrogen (extracted from the air) and hydrogen (obtained from natural gas)

• It can reach a dynamic equilibrium

Recall the conditions for the Haber process

• Temperature - 450 °C

• Pressure - 200 atmospheres

• Iron catalyst

predict how the position of a dynamic equilibrium is affected by changes in temperature

Temperature increase

○ Equilibrium moves in endothermic direction

○ Absorbs extra heat

Temperature decreases

○ Equilibrium moves in exothermic direction

○ Produces more heat

predict how the position of a dynamic equilibrium is affected by changes in pressure

More pressure

○ Equilibrium moves to the side with fewer moles

○ Reducing pressure

Less pressure

○ Equilibrium moves to the side with more moles

○ Increasing pressure

predict how the position of a dynamic equilibrium is affected by changes in concentration

More concentration

○ Equilibrium moves to the right side, to use up reactants

○ Producing more products

Less concentration

○ Equilibrium moves to the left side to conserve reactants

○ Producing less products