Acids Bases and Salts Chapter Notes - Chemistry for GCSE/IGCSE - Year 10

 Page 1


Acids, Bases and Salts
? Acids
? A substance which turns blue litmus paper red
? It has a sour taste and is corrosive
? Reacts with a base to form salt
? Disassociates in water to form H+ ions
? Conducts electricity
? Numbers less than 7 in the pH scale are acids
? The presence of H+ ions is what makes a solution acidic
? Examples of common acids
? Hydrochloric acid (HCl)
? Sulfuric acid (H2SO4)
? Nitric acid (HNO3)
? Ethanoic acid (CH3COOH)
? Reactions of Acids
? ? Acid + Base  Salt + Water
? ? Acid + Metal  Salt + Hydrogen
? ? Acid + Carbonate  Salt + Carbon Dioxide + Water
? Alkali
? A substance which turns red litmus paper blue
? Have a bitter taste and are slippery
? Numbers more than 7 in the pH scale are alkalis
? Disassociates in water to form OH- ions
? Bases
? A base which is water-soluble is referred to as an alkali
? Bases are usually oxides and hydroxides of metals
? Bases are substances which can neutralise an acid, forming a salt and water
? Examples of common alkali
? Sodium hydroxide/lye (NaOH)
? Potassium hydroxide (KOH)
? Calcium hydroxide {Ca(OH)}
? Ammonia (NH3)
Page 2


Acids, Bases and Salts
? Acids
? A substance which turns blue litmus paper red
? It has a sour taste and is corrosive
? Reacts with a base to form salt
? Disassociates in water to form H+ ions
? Conducts electricity
? Numbers less than 7 in the pH scale are acids
? The presence of H+ ions is what makes a solution acidic
? Examples of common acids
? Hydrochloric acid (HCl)
? Sulfuric acid (H2SO4)
? Nitric acid (HNO3)
? Ethanoic acid (CH3COOH)
? Reactions of Acids
? ? Acid + Base  Salt + Water
? ? Acid + Metal  Salt + Hydrogen
? ? Acid + Carbonate  Salt + Carbon Dioxide + Water
? Alkali
? A substance which turns red litmus paper blue
? Have a bitter taste and are slippery
? Numbers more than 7 in the pH scale are alkalis
? Disassociates in water to form OH- ions
? Bases
? A base which is water-soluble is referred to as an alkali
? Bases are usually oxides and hydroxides of metals
? Bases are substances which can neutralise an acid, forming a salt and water
? Examples of common alkali
? Sodium hydroxide/lye (NaOH)
? Potassium hydroxide (KOH)
? Calcium hydroxide {Ca(OH)}
? Ammonia (NH3)
? Chemical indicators
? Phenolphthalein
¦ Colourless(acid)
¦ Pink(alkali)
? Litmus
¦ Red(acid)
¦ Blue(alkali)
? Methyl orange
¦ red(acid)
¦ yellow(alkali)
? Ionic equations
? State symbols (important)
? Cancel spectator ions after balancing
? In neutralization reaction water is only product
? Oxides
? Elements combining with O2
? Types of oxides
¦ Acidic(non-metal oxides)
¦ Basic(metal oxides)
¦ Neutral
¦ Amphoteric(both acid and base)
? Acidic oxides
? ? ? C + 02  CO2        +H2O  H2CO3
? ? ? S + O2  SO2       +H20  H2SO3
? ? ? 4P + 5O2  2P2O5    +H20  H3PO4
? ? ? N + O2  NO2       +H2O  HNO3
? Metal/Basic oxides
? ? 4Na + 02  2Na2O
? ? 2Mg + O2  2Mgo
? ? 4Fe + 3O2  2Fe2O3
? ? 2Cu + O2  2CuO
? ? CuO  + HCl  CuCl2 + H2O
? Amphoteric oxides
? Behave like both acid and base
? ZnO/Al2O3/PaO
Page 3


Acids, Bases and Salts
? Acids
? A substance which turns blue litmus paper red
? It has a sour taste and is corrosive
? Reacts with a base to form salt
? Disassociates in water to form H+ ions
? Conducts electricity
? Numbers less than 7 in the pH scale are acids
? The presence of H+ ions is what makes a solution acidic
? Examples of common acids
? Hydrochloric acid (HCl)
? Sulfuric acid (H2SO4)
? Nitric acid (HNO3)
? Ethanoic acid (CH3COOH)
? Reactions of Acids
? ? Acid + Base  Salt + Water
? ? Acid + Metal  Salt + Hydrogen
? ? Acid + Carbonate  Salt + Carbon Dioxide + Water
? Alkali
? A substance which turns red litmus paper blue
? Have a bitter taste and are slippery
? Numbers more than 7 in the pH scale are alkalis
? Disassociates in water to form OH- ions
? Bases
? A base which is water-soluble is referred to as an alkali
? Bases are usually oxides and hydroxides of metals
? Bases are substances which can neutralise an acid, forming a salt and water
? Examples of common alkali
? Sodium hydroxide/lye (NaOH)
? Potassium hydroxide (KOH)
? Calcium hydroxide {Ca(OH)}
? Ammonia (NH3)
? Chemical indicators
? Phenolphthalein
¦ Colourless(acid)
¦ Pink(alkali)
? Litmus
¦ Red(acid)
¦ Blue(alkali)
? Methyl orange
¦ red(acid)
¦ yellow(alkali)
? Ionic equations
? State symbols (important)
? Cancel spectator ions after balancing
? In neutralization reaction water is only product
? Oxides
? Elements combining with O2
? Types of oxides
¦ Acidic(non-metal oxides)
¦ Basic(metal oxides)
¦ Neutral
¦ Amphoteric(both acid and base)
? Acidic oxides
? ? ? C + 02  CO2        +H2O  H2CO3
? ? ? S + O2  SO2       +H20  H2SO3
? ? ? 4P + 5O2  2P2O5    +H20  H3PO4
? ? ? N + O2  NO2       +H2O  HNO3
? Metal/Basic oxides
? ? 4Na + 02  2Na2O
? ? 2Mg + O2  2Mgo
? ? 4Fe + 3O2  2Fe2O3
? ? 2Cu + O2  2CuO
? ? CuO  + HCl  CuCl2 + H2O
? Amphoteric oxides
? Behave like both acid and base
? ZnO/Al2O3/PaO
? Neutral oxides
? Neither acid or base
? CO, N2O, H2O
Soluble salts Insoluble salts
All sodium
All potassium
All ammonium
All nitrates
All chlorides  except ? ? Lead(ll), Silver
All sulfates  except ? ? Barium, Calcium, Lead
Potassium,Sodium,Ammonium   except ? ? All Carbonates
Potassium, Sodium, Ammonium  except ? ? All hydroxides and oxides
Page 4


Acids, Bases and Salts
? Acids
? A substance which turns blue litmus paper red
? It has a sour taste and is corrosive
? Reacts with a base to form salt
? Disassociates in water to form H+ ions
? Conducts electricity
? Numbers less than 7 in the pH scale are acids
? The presence of H+ ions is what makes a solution acidic
? Examples of common acids
? Hydrochloric acid (HCl)
? Sulfuric acid (H2SO4)
? Nitric acid (HNO3)
? Ethanoic acid (CH3COOH)
? Reactions of Acids
? ? Acid + Base  Salt + Water
? ? Acid + Metal  Salt + Hydrogen
? ? Acid + Carbonate  Salt + Carbon Dioxide + Water
? Alkali
? A substance which turns red litmus paper blue
? Have a bitter taste and are slippery
? Numbers more than 7 in the pH scale are alkalis
? Disassociates in water to form OH- ions
? Bases
? A base which is water-soluble is referred to as an alkali
? Bases are usually oxides and hydroxides of metals
? Bases are substances which can neutralise an acid, forming a salt and water
? Examples of common alkali
? Sodium hydroxide/lye (NaOH)
? Potassium hydroxide (KOH)
? Calcium hydroxide {Ca(OH)}
? Ammonia (NH3)
? Chemical indicators
? Phenolphthalein
¦ Colourless(acid)
¦ Pink(alkali)
? Litmus
¦ Red(acid)
¦ Blue(alkali)
? Methyl orange
¦ red(acid)
¦ yellow(alkali)
? Ionic equations
? State symbols (important)
? Cancel spectator ions after balancing
? In neutralization reaction water is only product
? Oxides
? Elements combining with O2
? Types of oxides
¦ Acidic(non-metal oxides)
¦ Basic(metal oxides)
¦ Neutral
¦ Amphoteric(both acid and base)
? Acidic oxides
? ? ? C + 02  CO2        +H2O  H2CO3
? ? ? S + O2  SO2       +H20  H2SO3
? ? ? 4P + 5O2  2P2O5    +H20  H3PO4
? ? ? N + O2  NO2       +H2O  HNO3
? Metal/Basic oxides
? ? 4Na + 02  2Na2O
? ? 2Mg + O2  2Mgo
? ? 4Fe + 3O2  2Fe2O3
? ? 2Cu + O2  2CuO
? ? CuO  + HCl  CuCl2 + H2O
? Amphoteric oxides
? Behave like both acid and base
? ZnO/Al2O3/PaO
? Neutral oxides
? Neither acid or base
? CO, N2O, H2O
Soluble salts Insoluble salts
All sodium
All potassium
All ammonium
All nitrates
All chlorides  except ? ? Lead(ll), Silver
All sulfates  except ? ? Barium, Calcium, Lead
Potassium,Sodium,Ammonium   except ? ? All Carbonates
Potassium, Sodium, Ammonium  except ? ? All hydroxides and oxides
? Precipitation
? Stir the 2 reactants with H20
? Heat to form precipitate
? Wash precipitate to remove impurities
? Dab dry
? Reaction with acids
? Fill the beaker with H2SO4 then add excess Zn powder until it dissolves. No more H2
bubbles
? Filter to remove unreacted Zinc powder
? Take filtrate and heat to concentrate salt
? Heat till crystallization point, test vy dipping a cold glass rod in filtrate. Stop heating when
crystals form on the rod(solution is saturated)
? Cool solution for crystallization and filter to collect crystals
? Wash and dry with filter paper and distilled water
? Solubility for reaction(acid+metal)
? ? K, Na, Ca  very reactive, too dangerous to react with acids
? ? Mg, Al, Zn, Fe, Pb  Suitable and moderately reactive
? ? Cu, Ag  too unreactive
? Titration
? Apparatus: pipette, burette, conical flask
? Pipette the base into the conical flask
? Add indicator(phenolphthalein) to see exactly how much acid and base is present
? Run acid from burette into conical flask drop by drop
? Till end/neutralisation point(observe indicator)
? Repeat without indicator with precise amounts for purity of product
? Heat, saturate, crystallize, cool, wash, dry