Chemistry - Acids & Bases, Metals [MYE]

• Acids


  A chemical compound that releases hydrogen ions when dissolved in water
• Physical properties of acids

  • Sour
  • pH 0-6
  • Corrosive when concentrated
  • Litmus paper turns blue -> red
• Types of acids


  • Organic
  • Mineral
• Alkalis


  A chemical compound that releases hydroxide ions when dissolved in water
• Bases


  A chemical compound that reacts with acid to produce salt and water
• Common alkalis


  • Calcium oxide
  • Calcium hydroxide
  • Ammonium hydroxide
  • Potassium oxide
  • Potassium hydroxide
  • Sodium oxide
  • Sodium hydroxide
• Difference between base and alkali

  Bases are insoluble, alkalis are soluble
• Physical properties of alkalis

  • Bitter
  • pH 8-14
  • Litmus paper turns red -> blue
  • Corrosive when concentrated
  • Slippery
• Acid + Base reaction


  Produces salt + water
• Acid + Metal reaction


  Produces salt + hydrogen
• Acid + Metal Carbonate reaction


  Produces salt + water + carbon dioxide
• Alkali + Ammonium Salt reaction


  Produces salt + water + ammonia
• Test for oxygen: glowing splint (relight/rekindle)
• Test for hydrogen: lighting splint (extinguish with a 'pop' sound)
• Test for carbon dioxide: limewater (turns milky)
• Test for ammonia: damp red litmus paper (turns blue)
• Indicator


  A dye that changes colour in acid/alkaline substance
• Strong acids


  Completely ionise when dissolved in water
• Weak acids


  Partially ionise when dissolved in water
• Neutralisation


  A chemical reaction when acid and base react to produce salt and water
• Neutralisation applications


  • Nettle sting -> dock leaf
  • Bee sting -> baking soda
  • Wasp sting -> vinegar and lemon juice
• Titration


  Apparatus: Conical flasks, burette, pipette, retort stand & clamp

  Materials: Acid, alkali, indicator (methyl orange/thymolphthalein)
• Metal oxides


  • Basic
  • Amphoteric
• Basic metal oxides


  • Sodium hydroxide
• Non-metal oxides


  • Acidic
  • Neutral
• Acidic non-metal oxides


  • Sulfur dioxide
  • Nitrogen dioxide
• Neutral non-metal oxides


  • Water
  • Carbon monoxide
• Acid rain is caused by sulfur dioxide and nitrogen dioxide
• Effects of acid rain


  • Corrodes metal structures
  • Erodes buildings
  • Kills fish due to sensitivity
  • Causes soil leaching
  • Irritates human skin
• Preventing acid rain


  1. Remove sulfur from fossil fuels

  2. Reduce burning of fossil fuels

  3. Neutralise acidic gases/flue gases
• Haber process


  Raw materials: nitrogen, hydrogen

  Catalyst: Iron powder

  Used for manufacturing ammonia, which is used for fertiliser
• Contact process


  Stage 1: Furnace (sulfur + oxygen -> sulfur dioxide)

  Stage 2: Catalytic converter (sulfur dioxide + oxygen -> sulfur trioxide)

  Stage 3: Absorber (Sulfur trioxide + sulfuric acid -> oleum)

  Stage 4: Dilution (Oleum + water -> sulfuric acid)
• Sulfur trioxide cannot react with water due to exothermic reaction, violent reaction, and production of fine mist of sulfuric acid
• Types of decomposition


  • Hydrolysis (breaking down using water)
  • Electrolysis (breaking down using electricity)
  • Photolysis (breaking down using light)
  • Thermal (breaking down using heat)
• Calcium compound reactions


  Limestone (calcium carbonate) -> calcium oxide + carbon dioxide

  Quicklime (calcium oxide) + water -> calcium hydroxide

  Slaked lime (calcium hydroxide) + water -> calcium hydroxide (aqueous)
• Properties of metals


  • Silver, high density, solid at room temp, malleable, strong, sonorous, good conductor of heat and electricity
• Properties of non-metals


  • Colourful, low density, solid/liquid/gas at room temp, not malleable, not sonorous, brittle, insulator of heat and electricity
• Ores


  • Bauxite - Aluminium - Aluminium Oxide

  Galena - Lead - Lead Sulphide

  Cinnabar - Mercury - Mercury Sulphide

  Malachite - Copper - Copper Carbonate

  Limestone - Calcium - Calcium Carbonate

  Haematite - Iron - Iron Oxide
• Alloys


  • Brass - Copper + Zinc

  Bronze - Copper + Tin

  Sterling Silver - Copper + Silver

  Steel - Iron + Carbon

  Stainless Steel - Iron + Chromium + Nickel

  Solder - Lead + Tin

  Duralumin - Aluminium + Copper
• Iron Extraction with Carbon

  1. Carbon + oxygen —> carbon dioxide

  2. Carbon dioxide + carbon —> carbon monoxide

  3. Carbon monoxide + iron oxide —> iron + carbon dioxide