redox
reactions of metals
types of reactions in metal
metal+ water --> metal hydroxide + hydrogen
metal + steam --> metal oxide + hydrogen
metal + oxygen --> metal oxide
metal + acid --> salt + hydrogen
hydrochloric acid (HCI) --> Chloride (Cl-)
sulfuric acid (H2SO4) --> sulfate (SO4, 2-)
nitric acid (HNO3) -->nitrate (NO3 -)
Phosphoric acid (H3PO4) --> Phosphate (PO4, 3-)
reactivity order
magnesium(Mg)
aluminium(Al)
calcium (ca)
zinc(Zn)
Lithium(Li)
iron(Fe)
sodium(na)
copper(Cu)
potassium (k)
Silver (Ag)
gold (Au)
displacement
Displacement is the process where an element moves another element in a compound because it is more reactive
displacement can be seen manly in 2 reactions
Metal + metal oxide
metal + aqueous solutions of metal salts
exp: magnesium + iron oxide --> magnesium oxide + iron
copper nitrate + magnesium --> magnesium nitrate + copper
Displacement can be used to know the order of reactivity of different metals, as more reactive metals will displace less reactive metals
rusting
redox
oxidation
reduction
Gain of oxygen or loss of electrons
exp: Mg--> Mg 2+ + 2e-
magnesiums losses electrons and turns into a magnesium ion
exp2: 2Mg + O2 --> 2MgO
Magnesium gains oxygen so it gets oxidised
loss of oxygen or gain of electrons
exp: 2Cl + 2e- --> 2Cl-
exp2: Fe2O3 + C --> CO2 + Fe
chlorine gains electrons so it gets oxidised
iron is getting reduced as it oxygen has been removed
oxidising agent
oxidises substances
gets reduced
reducing agent
reduces substance
gets oxidised
redox
a reaction with both and oxidation reaction and a reduction reaction
corrosion
Metal slowly gets broken down by reacting with substances in the environment
rusting has many equations
one of them would be
iron + oxygen + water --> hydrated iron (iii) oxide
this is an example of a redox reaction
Only the surface of the metal gets corroded
oxygen, water and iron need to be present for rusting to take place
- surface of metal gets corroded
- if left long enough, the rust cape will fall off
- The metal corrodes again repeating the process
.
Ways to prevent rusting
Sacrificial methods
barrier methods
oil or grease the metal
electroplating
paint the metal
The paint creates a barriers stopping oxygen from getting to the iron
Similar to paint, it stops oxygen from reaching the iron, it is mostly used for moving parts
uses electrolysis to cover the iron in a thin layer of another metal.
Adding a more reactive metal to the iron so the more reactive metal reacts with the oxygen
galvanising
covers the iron in zinc (similar to electroplating)
how are metals extracted
Different metals are extracted in different ways depending on their reactivity
Methods of extraction
Extraction of reduction
found as pure element
Extraction by electrolysis
exp of metals
lithium
calcium
sodium
magnesium
potassium
exp of metals
iron
copper
zinc
exp of metals
gold
silver
This extraction involves displacing the molden metal from the other elements by displacing it using carbon as it is more reactive
reactions with dilute hydrocloric and sulfuric acid and metals
metals which are more reactive than hydrogen will react with the acids forming salts and hydrogen, this is a displacement reaction
rapid fizzing and colourless gas
reactions
copper+ oxygen--> copper oxide
orange/pink solid, glowing inside the tube
Magnesium + hydrochloric acid = magnesium chloride + hydrogen gas (Mg + 2HCl = MgCl2 + H2)
Iron + Sulfuric acid ⟶ Iron sulfate + Hydrogen [Fe(s)+H2SO4(aq)⟶FeSO4(aq)+H2(g)]
Copper + nitric acid --> copper nitrate + hydrogen
Aluminium + phosphoric acid --> aluminium phosphate + hydrogen
A salt is a compound that is formed when the hydrogen atom in an acid is replaced by a metal. For example if we replace the H in HCl with a potassium atom, then the salt potassium chloride is formed, KCl.
potassium + oxygen --> potassium oxide
calcium + water --> calcium hydroxide + hydrogen
sodium + steam --> sodium oxide + hydrogen