Reactions Flashcards
What is displacement
A more reactive metal will displace a less reactive metal from a compound
What affects a displacement reaction
The greater difference in reactivity between the two metals the greater the amount of energy released
What is oxidation
The loss of electrons from a substance . It is also the gain of oxygen by a substance e.g 2mg +O2 = 2mgo oil
What is reduction
The gain of electrons by a substance it is also the loss of oxygen from a substance e.g copper oxide can be reduced to form copper when it reacts with hydrogen. Copper oxide +hydrogen - copper and water rig
What is the oxidising agent
The chemical that causes oxidation
What is the reducing agent
Causes the other chemical to be reduced
What happens with aluminium +iron oxide
= iron + aluminium oxide
The aluminium has been oxidised this means iron oxide is the oxidising agent and iron oxide has been reduced so aluminium is the reducing agent
What is rusting
An oxidation reaction. The iron reacts with water and oxygen to form hydrated iron oxide(rust) . Iron +water +oxygen = hydrated iron oxide
Why does aluminium bot rust
Because it’s surface is protected by a natural layer of aluminium oxide
How canyon prevent rust
Stop oxygen or water reaching the metals surface . Like galvanising - the iron or steep object is coated in a thin layer of zinc that stops oxygen or water reaching the metal underneath , it also acts as a sacrificial metal as it is more reactive than iron so it oxidises in preference to the iron object
What is electrolysis
Electrolysis is the process by which ionic substances are decomposed into simpler substances when an electric current is passed through them
Why does electrolysis only work on ions
Electricity is the flow of electrons , for electrolysis to work the compound must contain ions , covalent compounds don’t work as they contain neutral atoms instead of ions. The ions must also be free to move which is possible when they are dissolved in water or melted
What happens during electrolysis
Positively charged ions move to the cathode they receive electrons and are reduced
Negatively charged ions move to the anode electrode , they lose electrons and are oxidised:
Where are metals and non metals attracted to
Metal is formed At the cathode because it is positive
Non metal element is formed at the anode because it is negative
What is a cathode
Negative electrode