Chemistry Syllabus

• mass


  Quantity of matter in an object
• molar mass


  Mass of one mole of a substance
• relative atomic mass or relative molecular / formula mass

  Ratio of the average mass of the atoms in a sample of an element to the mass of one atom of carbon-12
• Electrolysis


  Decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current
• Electrolytic cell

  • Anode is the positive electrode
  • Cathode is the negative electrode
  • Electrolyte is the molten or aqueous substance that undergoes electrolysis
• Transfer of charge during electrolysis

  1. Movement of electrons in the external circuit

  2. Loss or gain of electrons at the electrodes

  3. Movement of ions in the electrolyte
• Metals or hydrogen are formed at the cathode and non-metals (other than hydrogen) are formed at the anode
• Metal objects are electroplated to improve their appearance and resistance to corrosion
• An exothermic reaction transfers thermal energy to the surroundings leading to an increase in the temperature of the surroundings
• An endothermic reaction takes in thermal energy from the surroundings leading to a decrease in the temperature of the surroundings
• Enthalpy change, ∆H


  The transfer of thermal energy during a reaction. ∆H is negative for exothermic reactions and positive for endothermic reactions
• Activation energy, Ea


  The minimum energy that colliding particles must have to react
• Bond breaking is an endothermic process and bond making is an exothermic process
• A catalyst increases the rate of a reaction and is unchanged at the end of a reaction
• A catalyst decreases the activation energy, Ea, of a reaction
• Some chemical reactions are reversible as shown by the symbol ⇌
• • The rate of the forward reaction is equal to the rate of the reverse reaction
• The symbol equation for the production of ammonia in the Haber process is N2(g) + 3H2(g) ⇌ 2NH3(g)
• The symbol equation for the conversion of sulfur dioxide to sulfur trioxide in the Contact process is 2SO2(g) + O2(g) ⇌ 2SO3(g)
• The sources of the sulfur dioxide (burning sulfur or roasting sulfide ores) and oxygen (air) in the Contact process
• Collision Theory


  for a chemical reaction to occur, particles must collide with enough energy and in the correct orientation
• The typical conditions for the conversion of sulfur dioxide to sulfur trioxide in the Contact process are 450 °C, 200 kPa / 2 atm and a vanadium(V) oxide catalyst
• Oxidation number


  A Roman numeral used to indicate the oxidation state of an element in a compound
• Redox reactions


  Reactions involving simultaneous oxidation and reduction
• Oxidation


  Gain of oxygen
• Reduction


  Loss of oxygen
• Oxidation


  • Loss of electrons
  • Increase in oxidation number
• Reduction


  • Gain of electrons
  • Decrease in oxidation number
• Oxidising agent


  A substance that oxidises another substance and is itself reduced
• Reducing agent


  A substance that reduces another substance and is itself oxidised
• Aqueous solutions of acids contain H+ ions and aqueous solutions of alkalis contain OH- ions
• The neutralisation reaction between an acid and an alkali produces water, H+ (aq) + OH- (aq) → H2O (l)
• Acids


  Proton donors
• Bases


  Proton acceptors
• Strong acid


  An acid that is completely dissociated in aqueous solution
• Weak acid


  An acid that is partially dissociated in aqueous solution
• Hydrochloric acid is a strong acid, as shown by the symbol equation HCl (aq) → H+(aq) + Cl-(aq)
• Ethanoic acid is a weak acid, as shown by the symbol equation CH3COOH(aq) ⇌ H+(aq) + CH3COO-(aq)
• Acidic oxides


  Oxides that are acidic, including SO2 and CO2
• Basic oxides


  Oxides that are basic, including CuO and CaO