Chemistry In Industry (5) Flashcards
Most metals can’t be found as pure lumps. You have to __________ them from a ___________
Extract
Compound
Most metals are found in ________
Ores
Metals that are unreactive don’t tend to form ____________ with other elements
Compounds
Unreactive metals such as _______ are found uncombined
Gold
Most metals do react with other elements to form ______________, which can be found naturally in the Earth’s __________
Compounds
Crust
If a compound contains enough of the metal to make it worthwhile extracting, the compound is called a metal _____
Ore
There are _____________ amounts of metals ores - they’re finite resources
Limited
The more reactive a metal is, the ___________ it is to extract it from a compound
Harder
Metals often have to be separated from their _________
Oxides
Lots of common metals, like iron and aluminium, react with oxygen to form ___________
Oxides
Oxides are often like the ______ that the metals need to be extracted from
Ores
A reaction that separates a metal from the oxygen in its oxide is called a ___________ reaction
Reduction
In a reduction reaction, what is the substance that reduces the metal (and is oxidised) called
A reducing agent
What is the most common type of reduction reaction
Using carbon as a reducing agent to separate the oxygen from the metal. But metals can’t be used for all metals
How are metals which are lower in the reactivity series than carbon extracted
With carbon
This is done by heating the ore with carbon monoxide. Because carbon takes the oxygen away from metals which are less reactive than itself.
________ reactive elements form compounds more readily
More
Very reactive metals form very __________ ores. I.e it’s difficult to get the metal out of the compound
Stable
Metals that are more reactive than carbon have to be extracted using ______________
Electrolysis
Aluminium is more reactive than carbon so it has to be extracted from its ore using ________________
Electrolysis
Aluminium’s main ore is bauxite, after mining and purifying, a __________ powder is left. This is pure aluminium oxide ________
White
Al2O3
Al2O3 has a very high melting point so melting it would be very expensive. Instead the aluminium oxide is dissolved in molten ___________. This brings the temperature down making it easier and cheaper. The _____________ are made of graphite, a good conductor of electricity.
Cryolite
Electrodes
Electrolysis - turning ions into the ________ you want
Atoms
Molten aluminium oxide contains free ions - this means it’ll …
Conduct electricity
The positive Al3+ ions are attracted to the ____________ electrode where they ________ electrons and turn into ______________ atoms. These then sink to the bottom.
Negative
Gain
Aluminium
The negative O2- ions are attracted to the ___________ electrode where they ________ electrons. These oxygen atoms will then react together to form _____ or with the carbon anode as well to form ______
Positive
Lose
O2
CO2
As the positive ___________ electrode is constantly getting worn down by oxygen, it often needs ____________
Carbon
Replacing
What is a redox reaction
Where both reduction and oxidation take place
Equation for the decomposition of aluminium:
Aluminium oxide –> Aluminium + Oxygen
Decomposition of aluminium: Reaction at the negative electrode:
Al3+ + 3E- –> Al
Decomposition of aluminium: Reaction at the positive electrode:
2O2- –> O2 + 4E-
What is reduction
A gain of electrons
What is oxidation
A loss of electrons
Electrolysis uses a lot of _____________ which makes it expensive. Energy is also needed to _______ the electrolyte mixture. This is also expensive. The disappearing __________ electrodes need frequent replacement. This is expensive too.
Electricity
Heat
Positive
Iron is extracted from haematite by __________ in a blast furnace
Reduction
What are the 3 raw materials
Iron Ore
Coke
Limestone
The iron ore contains the iron
The coke is almost pure ___________. This is for reducing the iron oxide to iron _________.
What does the limestone do?
Carbon
Iron metal
Takes away impurities in the form of slag
Hot air is blasted into the furnace, making the ________ burn much faster than normal. This raises the temperature to about ______°C
Coke
1500
The coke burns and produces what?
Equation:
Carbon dioxide
C + O2 –> Co2
The Co2 then reacts with unburnt coke to form what?
Equation:
CO
CO2 + C –> 2CO
Carbon dioxide + carbon –> carbon monoxide
The carbon monoxide then reduces the iron ore to what?
Equation:
Iron
Carbon monoxide + iron(|||) oxide –> carbon dioxide + iron
The iron is __________ at this temperature and also very dense so it runs straight to the bottom where it’s tapped off
Molten
What is the main impurity of iron
What removes it
Sand (Silicon dioxide)
Removed by limestone
The limestone is decomposed by the heat into what
Calcium oxide and CO2
The limestone is decomposed by the heat into calcium oxide and CO2. This calcium oxide then reacts with the sand to form what?
Calcium silicate, or slag which is molten and can be tapped off
Calcium oxide reacting with calcium silicate equation:
CaO + Sio2 –> Casio3 (molten slag)
Cooled slag is solid and is then used for what?
Road-building
Fertiliser
Name 5 properties which iron and aluminium have in common
Both dense and lustrous (shiny) Both have high melting points Both strong and hard to break Both malleable Both good conductors of electricity and heat energy too
Adding other materials to iron can change its ______________. This makes it really useful. It makes it suitable for lots of different uses
Properties
Wrought iron is almost completely _______. Name its main property and use
Pure
Its malleable
Used to make ornamental gates and railings
You can mix iron with other elements to make __________
Alloys
Cast iron is very hard but _________.
What is it a mixture of?
Brittle
Iron, carbon and silicon
What is cast iron used for
Some cooking pans
Steel is an alloy made of mainly ________ and __________. It is ___________ than pure iron, but it can still be hammered easily into sheets and welded together. These properties mean that steel is great for making what
Iron, carbon
Harder
Car bodies
What is the main problem with iron
That it rusts
Stainless steel is an alloy made of chromium that doesn’t rust. What’s it used for
Knives, forks and cooking pans.
Aluminium is a typical metal. However, unlike iron, it doesn’t ___________ easily.
Corrode
Aluminium reacts very ___________ with oxygen in the air to from what?
A protective layer of aluminium _________ sticks firmly to the aluminium below and stops any further __________ from taking place
Quickly
Aluminium oxide
Reaction
Because aluminium doesn’t __________ it’s useful for products that come on contact with __________. E.g. drink cans - you wouldn’t want rust in your drink.
Corrode
Water
Aluminium is much less dense than iron which makes it ___________. This makes it useful when weight of the metal is important, e.g. aeroplanes.
Lighter
What is Casio3 the formula of
Molten slag
