Creation Of New Substances Flashcards
Electrolyte
Substance electrolysed
Electrolysis
Ionic compounds do not conduct electricity when solid because the ions are not free to move
Ionic compounds conduct electricity when molten or in an aqueous solution
Electrolysis is the decomposition of a substance by passing an electric current through it
Anode (electrolysis)
Positive electrode
Non-metal formed here (due to negative ions)
Non-metal loses electrons
Cathode (electrolysis)
Negative electrode
Metal is formed here, due to positive ions
Metal gains electrons
Electrolysis of aqueous solutions
A aqueous solution containing ions can be electrolysed
Water has an influence on the reaction
Negative electrode
Cathode
Hydrogen or a metal formed
Positive electrode
Anode
Oxygen or a non-metal formed
Metal more reactive than hydrogen
Hydrogen at cathode
Metal less reactive than hydrogen
Metal at cathode
Condensation reactions
Two molecules react -> form a larger molecule with the elimination of a small molecule (water)
Condensation polymers
Many monomers join together to make a polymer for each pair of monomers that join a small molecule is eliminated (water)
Polyesters (herylene)
Polyamides (nylon)
Disposing of polymers- landfill
Uses up valuable land, non-biodegradable
Disposing of polymers- incineration
They release alot of energy when burnt (useful)
Carbon dioxide produced as well as toxic gases
Disposing of polymers- recycling
Reduces disposal problems
The separation of different polymers is expensive and difficult
Addition polymers
A long- chain molecule formed by many small monomers joined together
Have a c-c double bond, this breaks allowing monomers to attach together
Burning fuel in cars
High temperatures means nitrogen + oxygen -> oxides of nitrogen
They dissolve in the air to form acid rain
Incomplete combustion
Lack of oxygen
Produces carbon monoxide
Catalytic converters
Carbon monoxide -> carbon dioxide
Oxides of nitrogen -> nitrogen and oxygen
Cracking
Long-chained hydrocarbons (alkanes) passed over a catalyst
(Silica or aluminium oxide) at 600-700*C
Many short-chained alkanes produced, at least one alkene
Problems of fractions
Far too many higher boiling point fractions
Not enough of the lower boiling point fractions
Cracking: converting long-chained hydrocarbons -> shorter-chained ones
To make more gasoline
Refinery gas uses
Bottles gas
Gasoline uses
Petrol for cars
Kerosene uses
Fuel for aeroplanes
Central heating boilers
Paraffin small heaters
Diesel oil uses
Diesel fuel for: buses, lorries, trains, cars
Fuel oil uses
Fuel for ships, industrial heating
Bitumen uses
Road surfaces, covering flat roofs
Factions of crude oil
Refinery gases Gasoline Kerosene Diesel oil Fuel oil Bitumen
Refining of crude oil
Crude oil heated until it is a vapour
Fed into the column at the bottom
Hydrocarbons with very high boiling points immediately turn to liquids and are tapped off at the bottom of the column
The other hydrocarbons rise up the column
As they rise they cool down
They will condense at different heights
Refinery gasses stay S gases and come out of the top of the column
Crude oil
A mixture of hydrocarbons mainly alkanes
Must be refined before having any use
First step is fractional distillation
Carried out in a fractionating column 400C at bottom 40C at top
aluminium characteristics
High strength to weight ratio
Good conductor of heat and electricity
Non-toxic
Resists corrosion
Uses of aluminium
Aeroplane bodies Overhead power cables Saucepans Food cans Window frames
Iron characteristics
Strong
Withstands collisions
Uses of iron
Car bodies
Iron nails
Ships
Bridges
Extraction of iron
Raw materials- iron ore, coke, limestone, air (mixed added at top)
Oxygen + coke —> carbon dioxide
Carbon dioxide + coke —> carbon monoxide
Carbon monoxide reduces iron (iii) oxide in iron ore
Iron melts, collects at bottom, tapped off
Calcium carbonate in limestone decomposes —> calcium oxide
Calcium oxide + silicon dioxide (impurity) —> calcium silicate
Calcium silicate melts, collects as molten slag, tapped off
Electrolysis of aluminium
Aluminium melts and collects at the bottom,tapped off
Some oxygen produced at positive electrode
Reacts with the graphite —-> carbon dioxide gas
Positive electrode must be replaced after burning away
Extraction of aluminium electrodes
Graphite (carbon)
Extraction of aluminium Electrolyte
Solution of aluminuim oxide dissolved in molten cryolite
Main ore of aluminium
Bauxite -> must first be purified before producing aluminium oxide
Aluminium oxide
High melting point
Must be dissolved in molten cryolite
Ore
Rocks with enough metal worth mining for
Unreactive metals in ores
Occur as elements
Ractive metals in ores
Found as compounds from which they must be extracted
Reactive metals
Electrolysis of the molten chloride/oxide
Most powerful method but very expensive
Medium/ lower reactivity metals
Heat with a reducing agent (carbon/carbon monoxide)
Gold/ silver -unreative
Occur naturally as the elements
