Redox, Rusting and Iron Flashcards
What three things can oxidation be defined as?
-Gain of oxygen
-Loss of hydrogen
-Loss of electrons
What three things can reduction be defined as?
-Loss of oxygen
-Gain of hydrogen
-Gain of electrons
What is a redox reaction?
A redox reaction is a reaction where both reduction and oxidation occur at the same time.
What two conditions are needed for rusting to occur?
Oxygen and water.
What is the fancy name for rust? What is the symbol equation?
Hydrated iron (III) oxide. (Fe2O3.xH2O).
What are the four barrier methods used to prevent rusting?
-Painting
-Oiling
-Plastic coating
-Metal plating
What needs to be done in order for metal plating to work properly?
The iron must be fully covered with a thin layer of metal.
Give some examples of when the barrier method ‘painting’ would be used?
Ships, railings and car bodies.
Give some examples of when the barrier method ‘oiling’ would be used?
Moving machinery parts, bike chains and gate hinges.
Give some examples of when the barrier method ‘plastic coating’ would be used?
Paper clips, fridge shelves and gym weights.
What is galvanising? Where would it be used?
When the iron is completely plated with zinc. Garden tools, buckets and chains.
What are food cans made from iron covered with to prevent rusting?
Tin!
What are ‘shiny’ bath taps made from iron covered with to prevent rusting?
Chromium.
In some cases, why might barrier methods not be used to reduce rusting? Where might this be the case?
If they are not suitable or are too expensive. With massive structures such as oil rigs and the hulls of ships made from steel.
How would oil rigs be prevented from rusting? Why is this done?
By placing zinc blocks on to the steel. Zinc is more reactive than iron and so it reacts with water and oxygen first.
What is sacrificial protection?
A metal that is more reactive than iron reacts in preference to the iron, so the iron does not rust.
How are the hulls of ships and petrol storage tanks protected form rusting?
Magnesium blocks are placed on to them.
If iron is the only metal that rusts, what happens to the other metals?
They corrode.
What’s is another name for limestone and what is the symbol equation?
Calcium carbonate. (CaCo3).
What is the main ore of iron and what does it contain?
Haematite and it contains iron (III) oxide (Fe2O3).
In the iron ore, how is the iron extracted?
In a blast furnace.
What does coke contain?
Carbon (C).
Why is iron a cheap metal?
Because the ore is abundant.
Why is iron used in many structures and bridges?
Because of its strength.
What is thermal decomposition?
The breaking down of a substance using heat.
In the producing of the reducing agent, what reduces the carbon dioxide and what does this then form?
Coke (C) and then forms Carbon monoxide (2CO).
In the producing of the reducing agent, what is the reducing agent?
The carbon monoxide.
What does the carbon monoxide reduce? How does it do this?
The iron (III) oxide and it does this by removing the oxygen from it.
When carbon monoxide reduces the iron (III) oxide, what products are formed?
Molten iron and carbon dioxide.
When limestone (calcium carbonate~CaCO3) is thermally decomposed, what products are formed?
Calcium oxide (CaO) and Carbon dioxide (CO2).
What impurities are present in the haematite ore and where are they from?
Silicon dioxide impurities from the sand.
Why does silicon dioxide react with calcium oxide?
Silicon dioxide is acidic and so reacts with calcium oxide to form calcium silicate.
What is the symbol equation when calcium oxide reacts with silicon dioxide?
CaO + SiO2 —> CaSiO3
When the molten slag and molten iron drip down to the bottom of the blast furnace, why do the not mix? What layer is on top?
Molten iron is more dense meaning the molten slag will be on the top.
What happens to the molten slag and molten iron in the blast furnace?
They are tapped off, as liquids through separate holes.
