Magnesium reacts with copper (11) oxide to give magnesium oxide and copper.
Mg (s) +CuO (s) MgO (s) + Cu (s)
Why is the above reaction, an eg for displacement reaction?
Answers
Answer:
Chemguide: Core Chemistry 14 - 16
An introduction to redox reactions
This page introduces redox (reduction and oxidation) reactions in terms of the transfer of oxygen and electrons. This is a key part of chemistry, and you should take your time over it to make sure you understand it.
I am assuming that you have read the page about reactions between metals and metal oxides because this page builds on that one.
Oxidation and reduction in terms of oxygen transfer
This is the easy bit!
If something gains oxygen, it is said to have been oxidised. So in the equation . . .
C + 2CuO CO2 + 2Cu
. . . the carbon has been oxidised to carbon dioxide.
The process of adding oxygen to something is known as oxidation.
The opposite of oxidation is called reduction.
In the equation, the copper(II) oxide has lost its oxygen. We say that it has been reduced to copper.
Oxidation and reduction always go hand-in-hand. If something is being oxidised, something else must be being reduced. A reaction in which oxidation and reduction is occurring is called a redox reaction.
Equipment
Apparatus
Eye protection (note 2)
Safety screens (note 2)
Crucible (note 3)
Pipeclay triangle
Tripod
Bunsen burner
Large sheet of hardboard to protect the bench (or heat resistant mats)
Scrap paper, 2 pieces
Chemicals
Magnesium powder (HIGHLY FLAMMABLE), 0.25 g (note 4)
Copper(II) oxide powder (HARMFUL, DANGEROUS FOR THE ENVIRONMENT), 0.25 g (note 4)
Health, safety and technical notes
Read our standard health and safety guidance.
Wear eye protection and use safety screens. The teacher should wear goggles or a face shield, and all students should wear eye protection throughout the demonstration.
Use a metal crucible rather than a ceramic one. Alternatively, use a steel ‘crown’ bottle top which has had the plastic insert burnt out (in a fume cupboard) – the bottle top must NOT be hot when the magnesium powder/copper oxide mix is added.
These amounts must not be exceeded unless you are covered by an Explosives Certificate issued by the police, in line with UK Explosives Regulations 2014.
Magnesium powder, Mg(s), (HIGHLY FLAMMABLE) – see CLEAPSS Hazcard HC059A.
Copper(II) oxide, CuO(s), (HARMFUL, DANGEROUS FOR THE ENVIRONMENT) – see CLEAPSS Hazcard HC026.
Procedure
Protect the bench with a large sheet of hardboard or heat resistant mats.
Set up a tripod with a pipeclay triangle and a crucible. Place safety screens around the apparatus.
Place the Bunsen burner under the crucible.
Move the class to the back of the room, with the safety screen between them and the experiment. They should wear safety glasses. Warn them not to stare at the crucible.
Gently mix the small portions of magnesium and copper(II) oxide by putting them on a piece of scrap paper and repeatedly pouring back and forth onto another piece of scrap paper. Add the mixture to the crucible.
Light the Bunsen burner (away from the crucible) with the air hole open and then place the Bunsen flame under the crucible. Move quickly to a metre or two in front of the safety screen.
After one or two minutes (be patient) a vigorous reaction occurs. Do not stare at the crucible as the flash is bright.
If nothing happens, do NOT return to the apparatus but leave it for up to 15 mins. Then turn off the gas at the stopcock, allow the apparatus to cool and then place the crucible and contents in a large beaker of water.
Do NOT be tempted to use other metal oxides.
Teaching notes
The reaction is:
Copper oxide + magnesium → copper + magnesium oxide
This shows that magnesium is higher in the reactivity series than copper.
Most of the products are vaporised in the above reaction.