Redox Flashcards
What is a redox reaction?
A redox reaction is a reaction in which oxidation and reduction occur in the same reaction.
What is oxidation?
- The gain of oxygen
- The loss of hydrogen
- The loss of electrons
What is reduction?
- The loss of oxygen
- The gain of hydrogen
- The gain of electrons
Explain the oxidation reaction - Combustion
- Combustion.
This is when oxygen combines with fuels e.g. coal, oil etc., to produce carbon dioxide, water and ENERGY.
It is to produce energy that the fuels are burnt.
Methane + oxygen carbon dioxide + water + ENERGY
Explain the oxidation reaction - Rusting
- Rusting
This is an undesirable oxidation process.Iron + water + oxygen iron (iii) oxide
Explain the oxidation reaction - Burning of metals and non-metals to form oxides
- Burning of metals and non-metals to form oxides:
Burning magnesium:
Magnesium + Oxygen —> Magnesium Oxide
2Mg + O2 —> 2MgO
Explain the reduction reaction - Electrolysis
- Electrolysis: -
Aluminium oxide is reduced to aluminium using electrolysis
Aluminium oxide aluminium + oxygen
The oxygen is removed by ELECTROLYSIS.
Explain the reduction reaction - Blast Furnace
- Blast Furnace
Iron is produced in the blast furnace by the
reduction of iron oxide
Iron (iii) oxide + Carbon monoxide iron + carbon dioxide
Explain the reduction reaction - Haber process
- Haber Process:
Nitrogen and hydrogen react together to produce ammonia
Nitrogen + hydrogen ammonia
Explain the reduction reaction - Copper (ii) oxide
- Reduction of copper (II) oxide to copper using hydrogen:
Copper oxide + hydrogen copper + Steam
Observations:
* Red solid changes to black
* Condensation on the glass tube
What is the chemical name for rusting?
The chemical name for rust is hydrated iron (III) oxide.
What condition are needed for rusting?
Water, air and Iron
Explain the two ways to prevent rusting?
Most ways of preventing rusting are simply barrier methods, which stop the moist air from coming into contact with the iron.
Sacrificial protection is when a metal more reactive than iron is plated onto an iron object, it will react first, sacrificing itself and protecting the iron from rusting
Explain the barrier method of preventing rusting - Painting
This is relatively cheap, and can be used to cover large areas e.g. bridges and gates. The paint prevents air or moisture getting at the iron.
Explain the barrier method of preventing rusting - Greasing
This is suitable for covering moving parts of machinery that would otherwise rub away paint. E.g. car engines, and bicycle chains. The oil prevents air getting at the item.
Explain the barrier method of preventing rusting - Plastic Coating
The iron object is covered with a plastic covering to prevent air and water from reaching the iron. E.g. handle bars on a bicycle.
Explain the barrier method of preventing rusting - Stainless Steel
If iron is mixed with other substances, its properties will change. When iron is mixed with nickel and chromium, it becomes much harder, and no longer rusts. It is called stainless steel, and is used for car parts, kitchen sinks, and cutlery.
Explain the barrier method of preventing rusting - Tin Plating
In this method, tin is used to coat the iron. Tin is used because it is less reactive, and non-toxic. The tin is deposited using electrolysis.
Explain the barrier method of preventing rusting - Chromium Plating
Chromium, like tin, is plated onto the iron by electrolysis. Chromium is a shiny metal, and it is used in car bumpers.
Explain the sacrificial protection method of preventing rusting - Galvanising
In this method, iron is coated with a layer of zinc, by dipping the object into molten zinc.
As zinc is more reactive than iron, even if the coating is scratched to expose the iron, the zinc, rather than the iron will react with the air.
Galvanising is suitable for items that will be stored outside, e.g. dustbins and wheelbarrows.
Explain writing redox reactions in terms of electrons?
Look in book
