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

  1. surface of metal gets corroded
  1. if left long enough, the rust cape will fall off
  1. 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