Chemistry - Unit 2c - Metals, Extraction and Energy

Whats the order of the reactivity series?

Potassium, sodium, calcium, magnesium, aluminium, CARBON, zinc, iron, tin, HYDROGEN, copper, silver and gold

What is an ore?

A mineral compound rock that contains enough metal to make it economically worthwhile extracting the metal from it

How can you tell what metals are in an ore?

By looking at its chemical formula

Where are most of the metal ores found?

In the earths crust

Whats an uncombined element?

Metals that are found in their native form and can be mined straight from the ground, but need to be refined

What does refined mean?

To remove impurities or unwanted elements from a substance

The more reactive the metal…

…. the harder they are to extract from their ores

Which elements can be extracted from their ores by reduction using carbon and why?

(Zinc, iron, tin, copper and silver) - because these metals are lower on the reactivity series than carbon. This is because carbon can only take the oxygen from metals which are less reactive than carbon itself

What is oxidation in terms of extraction?

The reaction with or addition of oxygen

What is reduction in terms of extcration?

The removal of oxygen

Where are ion ores found around the world?

Australia, Canada and Milom

What are the raw materials for ion extraction?

Iron ore - contains iron

Coke - a fuel made from almost pure carbon to produce carbon minoxide for reduction of ironoxide to iron metal

Limestone - takes away impurities in slag form

Explain how we reduce an iron ore to iron

Hot air blasted into furnace to provide oxygen so coke burns faster, this raises temp to 1500

The coke burns in combustion to produce CO2

The CO2 reacts with unburnt coke in combustion to produce CO

CO reduces iron ore to produce iron and carbon dioxide

Iron is now molten and v dense so runs to bottom of furnace where its tapped off

Limestone decomposes by heat to form calcium oxide and carbon dioxide

The calcium oxide reacts with silicon dioxide(sand) in a neutralisation reaction to form calcium sulfate(slag) which is molten and can be tapped off

Why is the extraction of iron a continuous process?

the iron ore, coke and limestone are continuously added to furnace as molten iron and slag are removed. This means you dont have to reheat the furnace everytime - saves time and money

What’s a displacement reaction?

A more reactive metal displaces a less reactive metal from a solution if it’s salt

What’s oxidation in terms of electrons?

Loss of electrons

What’s reduction In Terms of electrons?

Gain of electrons

What’s a redox reaction?

A reaction where oxidation and reduction occur simultaneously

What happens in a displacement reaction?

More reactive metal is oxidised and the less reactive metal is reduced. The more reactive metal will replace the less reactive metal in the compound

What happens if you put a less reactive metal with a more reactive metal salt?

Nothing will happen

What’s a competition reaction?

If you heat up more reactive metal with a less reactive metal oxide, the more reactive metal removes oxygen(reduction) from the oxide

What’s a thermic reaction?

Specific type of competition reaction, usually involves aluminium, that is highly exothermic - useful for welding

What is electrolysis?

Splitting up ions in an ionic compound(in molten or dissolved) using electricity

What happens when ions move to the left roses and react?

The compound decomposes and the ions create a flow of electricity

What’s an electrode and electrolysis

Both are conductors of electricity

Electrode - solid submerged into into electrolyte

Electrolyte - liquid/solution

How do you set up electrolysis?

Power supply is connected to electrodes with wires. The end of the electrodes are placed inside test tubes. Any gases produced at electrodes will be collected inside test tubes

How is water split in electrolysis and what are the products?

At the cathode, H* ions are reduced to form hydrogen gas (2H* + 2e- —> H2)

At the anode, hydroxide ions are oxidised and form oxygen has (2OH- —> O2 + 2H* + 4e-)

What’s the overall equation for the electrolysis of water?

2H(2)O —→ 2h(2) + O(2) - forms 2 hydrogen molecules for every oxygen molecule. S o the volume of the hydrogen gas is always twice the voume of the oxygen gas

Whats a negative to using electrolysis to extract metals from their ores?

Its very expensive as lots of energy is required to melt the ore and produce the required current

Explain how aluminum is extracted from its ore using electrolysis?

Aluminium oxide has a very high melting point so its dissolved in molten cyrolite. Dissolving it in cryolite requires a lower emlting point so reduces energy needed. Positive AI3+ ions go through reduction at cathode and Negative O2- ions go through oxidation at the anode

Why does the carbon anode need to be replaced regularly during electrolysis that involves oxygen?

The oxygen reacts with the carbon to make carbon dioxide

Whats the test for hydrogen?

“Sqeaky pop” with a lighted split

Whats the test for oxygen?

it will relight a glowing splint

How do you purify copper and why?

Copper is impure when its extracted using reduction with carbon. So electrolysis is used to purify it. The anode is big lump of impure copper and cathode is thin pure copper. The electrolyte is copper sulfate. Impure copper anode is oxidised to produce copper ions and copper ions are reduced at cathode to produce layer of pure copper. Any impurities from impure anode will sink to form sludge

What are 5 factors need to be considered for finding a site for a metal extraction plant?

• Built by coast for importing raw materials

• Built not near urban areas - plants are loud/ air pollution

• Close enough to towns/cities for employment

• Direct power supple nearby - lots of electricity needed

• Good transport links near by (railway line/motorways)

How are extraction plants sustainable?

Recyling materials saves money as the process often only uses small fraction of energy needed to refine material from scratch - reduces greenhouse emissions and energy and costs

What is a use of iron?

Wrought iron is almost pure iron so its malleable and used to make gates and railings. However it corrodes easily

What is a use of Alluminium?

Doesnt corrode easily - reacts with oxygen to make aluminium oxide as a protective layer so good for window frames

Non toxic - food cans

Less dense - bicyle and aeroplanes

What is uses of Copper?

Used in electrical components and wiring because it has low resistance and efficient at transferring electricity

Used in heating systems such as underfloor heating a it allows heat transfer to its surroundings

Has attractive colour and lustre so used for decortaion

What are use of Titanium?

Low density so doesnt corrode easily and is very hard.

Lightweight so used for bicycle frames and aeroplanes

Whats an alloy?

A mix of molten metals with sometimes carbon

Why are alloys stronger than pure metals?

new atoms will disort the layers of metal atoms , making it harder for layers to slide over each other

Where are transition metals on periodic table?

Metals that sit in the middle

What are properties of transition metals?

Hard, strong, shiny and malleable materials that conduct heat/electricity

High melting point (except mercury -liquid at room temp.)

High densities

They have more thanone iron

What colour precipitates are produced when Iron(III) , Iron (II) and copper react with aqueous hydroxide solutions?

Iron(III) - brown

Iron (II) - pale green

Copper - blue

What are spectator ions?

Ions that arent included in precipitation reactions

What is activation energy?

Minimum amount of energy required to break bonds and for the reaction to start

How do you find activation energy?

The energy difference between the reactants and highest point on the curve

Bond breakin is …

Bond formation is …..

… endomthermic process

… exothermic process

How do you calculate the overall energy change for a reaction?

Overall energy change = energy required to break bonds - energy released by forming bonds

What do the resulst of finding the overall energy change tell us?

Positive energy - endothermic

Negative energy - Exothermic