GCSE CCSE Chemistry Acids,Bases and Salts Complete Revision Summary

This page contains the detailed and easy notes for GCSE CCEA Chemistry Acid Bases and Salts for revision and understanding Acid Bases and Salts .

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GCSE CCEA Chemistry Acid Bases and Salts Complete Revision Summary

Acid Bases and Salts

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Acid Bases and Salts

  • Reactivity of Metals
  • Reactivity Series
  • Extraction of Metals
  • Acids and Bases
  • Neutralization
  • Making Soluble Salts
  • Making Insoluble Salts
  • Titrations
  • Electrolysis
  • Electrolysis of molten compounds
  • Electrolysis of aqueous solutions
  • Electrolysis of Aluminium

REACTIVITY SERIES

Metal + Dilute Acids = Salt + Hydrogen

Metal + Water = Metal Hydroxide + Hydrogen

DISPLACEMENT REACTION

More reactive metal will displace the less reactive metal from its salt solution.

Magnesium(More reactive metal)  + Zinc sulphate (Less reactive salt )  = Magnesium sulphate (More reactive metal displaces the less reactive) + Zinc

Lead + Magnesium Sulphate                =                No reaction

(Less reactive metal cannot displace the more reactive metal)

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METAL EXTRACTION

MINERALS

Minerals are the rocks which contains metal.

ROCKS

Rocks are the minerals from which metals can be extracted profitably.

REDUCTION OF METAL OXIDES

Since most of the metals exist in the form of oxides, they can be extracted by reducing the ore.

By HYDROGEN

All the metal below hydrogen can be reduced by hydrogen

BY CARBON

All metal below carbon can be extracted by carbon

BY ELECTROLYSIS

Metals that are above carbon and hydrogen will be extract by Electrolysis
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OXIDATION AND REDUCTION

Oxidation

  • Gain of Oxygen
  • Loss Of hydrogen
  • Loss of electrons

C + O2                  CO2

CH4 + O2                  CO2 + H2O

2Cl                   Cl2 + 2e

Reduction

  • Loss of Oxygen
  • Gain of Hydrogen
  • Gain of electrons

CuO + Zn                  Cu + ZnO

H2S + Cl2                  2HCl + S

Na+ + e                   Na

Copper Oxide + Hydrogen                     Copper + Water

CuO + H2                  Cu + H2O

Zinc Oxide + Carbon Zinc + Carbon Dioxide

2ZnO + C                  2Zn + CO2

ACIDS BASES and ALKALI

The substance which have pH less than 7.

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Strong Acids

  • They completely dissociated in water to release H+ ions
  • Hydrochloric Acid HCl
  • Sulphuric Acid H2SO4
  • Nitric Acid HNO3
  • Phosphoric Acid H3PO4
  • HCl H+ + Cl
  • pH = 1-3

Weak Acids




  • They are partially dissociated in water to release H+ ions
  • Vinegar: Ethanoic Acid
  • Lemon: Citric Acid
  • CH3COOH CH3COO + H+
  • pH = 5-7

The substance which have pH greater than 7.

  • Metal Oxides, Metal Hydroxides, Metal Carbonates
  • Lithium Oxide, Lithium Carbonate, Lithium Hydroxide
  • Alkali are the soluble bases. So bases that can dissolve in water.
  • Alkali metal hydoxide
  • They release hydroxide ions when dissolved in water.

INDICATORS

AcidsBases
Taste SourTaste Bitter
Not soapyFeels soapy
have pungent smalldo not have a pungent smell
When ionize give hydrogen ionsGive hydroxide ions
Turns blue litmus redTurns red litmus Blue
eg Hydrochloric Acideg Sodium Hydroxide
Sulphuric Acid 

NEUTRALIZATION REACTION

Acid + Base                  Salt + Water

                         Metal                  Acid

Hydrochloric Acid -makes chloride salt

Sulphuric Acid – makes sulphate salt

Nitric Acid – makes nitrate salt

Eg

Sodium Chloride + Water                  Sodium Hydroxide + Hydrochloric Acid

NaOH + HCl                  NaCl + H2O

Potassium Oxide + Sulphuric Acid                            Potassium Sulphate + Water

K2O + H2SO4                   K2SO4 + H2O

Magnesium Hydroxide + Nitric Acid                   Magnesium Nitrate + Water

Mg(OH)2 +2HNO3                   Mg(NO3)2 +2H2O

Calcium Carbonate + Sulphuric Acid              Calcium Sulphate + Carbonate + Water

CaCO3 + H2SO4                          CaSO4 + H2O + CO2

REACTIONS OF ACIDS

  • Metal + Acid = Salt + Hydrogen
  • Metal Oxide + Acid = Salt + Water
  • Metal Hydroxide + Acid = Salt + Water
  • Metal Carbonate + Acid = Salt Water + CO2

2Na + 2HCl                  2NaCl +H2

Making Insoluble salts

Mix two soluble acids and Bases

The salt will come out as a precipitate

The precipitate is then filtered and dried.

The filter paper will contain an insoluble salt.

To determine the exact volume of acid and base required to make the salt, titration is carried out.

Making Soluble Salts

Mix the insoluble base into the aqueous solution of the acids.

Dissolve the base into the acid until no base can be dissolved.

Filter the solution to remove excess undissolved base.

The run off is then crystallized to remove all the water.

After evaporation the crystals will collect at the size of the vessel.

The crystals can then be dried.

ELECTROLYSIS

  • Electrolysis – The breaking of ionic compound by passing electricity.
  • Electrolyte – The substance that undergoes Electrolysis
  • Electrode – The two conducting rods dipped in an electrolyte
  • Cathode – Where Cations (+ve charge ions) go. So it is negatively charge electrode
  • Anions – Where anions (-ve charge ions) go. So it is positively charged.

ELECTROLYSIS OF MOLTEN IONIC COMPOUNDS

Ionic compounds conduct Electricity when in molten or in solution as the ions are free to move when they’ are in solvent or dissolved in water.

Molten Sodium Chloride

NaCl                   Na+(goes towards cathode) + Cl(goes towards anode)

Cathode                    Reduction

Na+ + e                  Na(s)

Anode                        Oxidation

2Cl                  Cl2(g) + 2e

O – Oxidation

I – Is

L – Loss

R – Reduction

I – Is

G – Gain

ELECTROLYSIS IN SOLUTIONS

In Solution the water also gets ionized and dissociate into H+ and OH- which also competes with the ionic compounds ions to discharge.

Sodium Chloride Solution

Ions

H+ + OH

Na+ + Cl

At Cathode

2H+ + 2e–                          H2(g)

Rule – At the cathode, the element with least reacitivity will get discharged and gains electrons.

For that we have to look at the reactivity series

At Anode

2Cl                 Cl2 + 2e

For Anode, the rule is – Halide> OH > other negative ions

Remaining Solution

Na+ + OH

Potassium Sulphate solution

Ions

K+ + SO42-

H+ + OH

At Cathode

2H+ + 2e–                          H2

At Anode

4OH                 O2 + 2H2O + 4e

Remaining Solution

K2SO4

ELECTROLYSIS OF ALUMINIUM OXIDE

Bauxite an ore of aluminium is used which contains aluminium in the form of aluminium oxide.

Al2O3                 Al3+ O2-

Bauxite is mixed with cryolite. Cryolite lowers the melting point of aluminium oxide making it melt at a lower temperature.

At Anode

2O2-                  O2 + 4e

Oxygen evolved reacts with graphite electrode forming carbon dioxide. Therefore, they are used up and needs regular replacing

At Cathode

Al3+ + 3e–                          Al(s)

O2 + C                 CO2
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