redox 1

• What does oxidation involve?

  Oxidation involves the loss of electrons.
• What does reduction involve?

  Reduction involves the gain of electrons.
• What acronym is used to remember the redox rule?

  The acronym is OILRIG (oxidation is loss, reduction is gain).
• What does the oxidation number indicate?

  The oxidation number indicates the oxidation state of an element or ionic substance.

  
• What are the rules for assigning oxidation numbers?

  • The oxidation number of an element is zero.
  • Oxidation numbers in a neutral compound add up to zero.
  • Oxidation numbers in a charged compound add up to the total charge.
  • Hydrogen has an oxidation number of +1.
  • Oxygen has an oxidation number of -2.
  • Halogens have an oxidation number of -1.
  • Group I metals have an oxidation number of +1.
  • Group II metals have an oxidation number of +2.

  
• What is an exception to the oxidation number rules for oxygen?

  Oxygen has an oxidation number of -1 in peroxides.
• What is an exception to the oxidation number rules for hydrogen?

  Hydrogen has an oxidation number of -1 in metal hydrides.

  
• How can oxidation numbers be used in a reaction?

  They can be used to work out the oxidation number of species or elements in a reaction or compound.

  
• How can the oxidation number of sulfur be determined in a compound?

  By using known oxidation numbers and setting up an equation based on the total oxidation number.

  
• What do Roman numerals indicate in chemical compounds?

  Roman numerals indicate the oxidation number of an element with a variable oxidation state.
• What does Copper(II) sulphate indicate about copper's oxidation number?

  It indicates that the oxidation number of copper is +2.
• What does Iron(II) sulphate(VI) indicate about iron and sulfur's oxidation numbers?

  It indicates that the oxidation number of iron is +2 and the oxidation number of sulfur is +6.
• How can oxidation numbers help in deducing the formula of compounds?

  • Oxidation numbers indicate the charge of elements.
  • Knowing oxidation numbers allows for the deduction of the overall charge of the compound.
  • This helps in determining the correct formula for the compound.

  
• How are elements arranged in the periodic table?

  Elements are arranged by proton number and their orbitals.
• What do orbitals correspond to in the periodic table?

  Orbitals correspond with blocks on the Periodic Table.
• Why do elements within the same block react in similar ways?

  Because their outermost electron is in the same type of orbital.
• What are the patterns in oxidation number in the periodic table?


  • s block elements (groups 1 and 2) generally lose electrons and form positive oxidation numbers.
  • p block non-metals generally gain electrons and form negative oxidation states.

  
• What is the role of an oxidising agent?

  An oxidising agent accepts electrons from the species that is being oxidised.
• What happens to the oxidation number of an oxidising agent?

  The oxidation number decreases (gets more negative).

  
• What is the role of a reducing agent?

  A reducing agent donates electrons to the species being reduced.
• What happens to the oxidation number of a reducing agent?

  The oxidation number increases (gets more positive).

  
• What are redox reactions?

  • Reactions where oxidation and reduction occur simultaneously.
  • One species loses electrons while another gains them.
  • Known as redox reactions (reduction - oxidation).
• How can oxidation numbers help identify disproportionation reactions?

  They enable you to determine if a species is both oxidised and reduced.
• What occurs in a disproportionation reaction?

  A species is both oxidised and reduced, showing both an increase and a decrease in oxidation number.
• What is an example of a disproportionation reaction involving chlorine?

  Chlorine reacts with cold water to produce chlorate(I) ions (ClO^-) and chloride ions.

  
• What are half equations used for in redox reactions?

  Half equations show the separate oxidation and reduction reactions that occur in a redox reaction.
• What is the method for balancing half equations?

  1. Balance all species excluding oxygen and hydrogen.
  2. Balance oxygen using H₂O.
  3. Balance hydrogen using H⁺ ions.
  4. Balance charges using e^- (electrons).
• What must be true for half equations to be combined in a redox reaction?

  The number of electrons must be the same for both half equations.
• What should be done after combining half equations in a redox reaction?

  The electrons should be cancelled out on each side of the equation.
• What is the definition of oxidation number?


  The charge of an ion or a theoretical charge of an atom in a covalently bonded compound assuming the bond becomes ionic.
• What occurs during oxidation in a chemical reaction?

  Loss of electron and an increase in oxidation number.
• What is the process of reduction in a redox reaction?

  Gain in electrons and a decrease in oxidation number.
• What does the term redox refer to?

  A reaction that involves oxidation and reduction.
• What is the role of an oxidising agent in a redox reaction?

  It accepts electrons and gets reduced, causing the oxidation of other species.
• What does a reducing agent do in a redox reaction?

  It donates electrons and gets oxidised, causing the reduction of other species.
• What are half-equations in redox reactions?

  • A full redox equation can be split into two half-equations: oxidation and reduction.
  • Useful for balancing complex redox reactions.
• How can the redox reaction involving \( \text{MnO}_4^- \) and \( \text{C}_2\text{O}_4^{2-} \) be split into half-equations?


  Reduction: \( 2 \text{MnO}_4^- + 16 \text{H}^+ + 10 e^- \rightarrow 2 \text{Mn}^{2+} + 8 \text{H}_2\text{O} \); Oxidation: \( 5 \text{C}_2\text{O}_4^{2-} \rightarrow 10 \text{CO}_2 + 10 e^- \)
• What is the balanced redox equation for the reaction involving \( \text{MnO}_4^- \), \( \text{C}_2\text{O}_4^{2-} \), and \( \text{H}^+ \)?

  \( 2 \text{MnO}_4^- + 5 \text{C}_2\text{O}_4^{2-} + 16 \text{H}^+ \rightarrow 2 \text{Mn}^{2+} + 5 \text{CO}_2 + 8 \text{H}_2\text{O} \)
• What is disproportionation in a redox reaction?

  A redox reaction involving an element in a single species being simultaneously oxidised and reduced.
• Provide an example of a disproportionation reaction.


  \( \text{Cl}_2 + \text{H}_2\text{O} \rightleftharpoons \text{HClO} + \text{HCl} \)