Unit 3 - Q. based on Spec.

Redox

1. What are redox reactions in terms of electron transfer?

2. How can redox systems be represented in terms of ion/electron half-equations and as half cells in cell diagrams?

3. What is the concept of standard electrode potential, and what role does the standard hydrogen electrode play?

4. How are simple electrochemical cells formed by combining electrodes, specifically metal/metal ion electrodes and electrodes based on different oxidation states of the same element?

5. What is the significance of the concept of cell EMF in terms of the feasibility of reactions?

6. What are the principles of the hydrogen fuel cell, and what are its benefits and drawbacks?

7. How do you construct ion/electron half-equations, for example, for the reduction of acidified Cr₂O₇^2‒ to Cr³⁺ and acidified MnO₄^‒ to Mn²⁺, as well as the oxidation of S₂O₃^2‒ to S₄O₆^2‒?

8. How can half-equations be combined to give a stoichiometric redox equation?

9. What is the redox reaction between Cu²⁺ and I^‒, and how is the liberated iodine determined with S₂O₃^2‒?

10. How is a redox titration carried out?

    Last tested: 30/05

p - block

1. What is the amphoteric behaviour of p-block elements as demonstrated by the reactions of Al³⁺/Al and Pb²⁺/Pb?

2. How does the stability of inert pair cations change on descent of Groups 3, 4 and 5?

3. How can some Group 3 elements form compounds with fewer than eight electrons in their valence shells, and how can some elements of Groups 5, 6 and 7 form compounds with more than eight?

4. What is the structure and bonding in Al₂Cl₆ and how is it related to the formation of donor-acceptor compounds such as NH₃.BF₃?

5. How do the bonding and structure in hexagonal and cubic boron nitride relate to their properties and uses?

6. What is the change in relative stability of oxidation states II and IV down Group 4, specifically in the reactions of CO as a reducing agent with oxides and Pb(IV) as an oxidising agent in the reaction of PbO₂ with concentrated hydrochloric acid?

7. What are the nature, physical properties and acid-base properties of CO₂ and PbO?

8. What changes occur in the types of bonding down Group 4 as shown by the chlorides CCl₄, SiCl₄ and PbCl₂ and their reactions with water?

9. What are the reactions of Pb²⁺_(aq) with aqueous NaOH, Cl^‒ and I^‒?

10. What are the reactions of Cl₂ with both cold and warm aqueous NaOH, and what disproportionation reactions are involved?

11. How does the bleaching and bactericidal action of Cl₂ and chlorate(I) (ClO^‒) result from their oxidising power?

12. What are the differences in behaviour of NaCl, NaBr and NaI with concentrated sulfuric acid in terms of the formation and subsequent reactions of HX?

Last tested: 30/05

d - block

1. How do d-block elements attain various oxidation states in their compounds?

2. What are the most important oxidation states of Cr, Mn, Fe, Co and Cu, and what are the colours of aqueous solutions of compounds containing Cr³⁺, CrO₄^2‒, Cr₂O₇^2‒, MnO^4‒, Co²⁺, Fe²⁺, Fe³⁺ and Cu²⁺?

3. What is the bonding in tetrahedral and octahedral complexes?

4. What is the origin of colour in transition metal complexes, as exemplified by octahedral 6 coordinate species such as [Cu(H₂O)₆]²⁺ and [Fe(H₂O)₆]³⁺, in terms of the splitting of d-orbitals?

5. What is the idea of ligand exchange, and how can it lead to a change in coordination number, as exemplified by the reactions of [Cu(H₂O)₆]²⁺ and [Co(H₂O)₆]²⁺ with concentrated HCl?

6. What are the colours and formulae of the approximately octahedral complex ions [Cu(H₂O)₆]²⁺, [Cu(NH₃)₄(H₂O)₂]²⁺ and [Co(H₂O)₆]²⁺, and the approximately tetrahedral ions [CuCl₄]^2‒ and [CoCl₄]^2–?

7. What are the catalytic properties of many transition metals and their compounds, specifically heterogeneous catalysis as a result of surface adsorption and homogeneous catalysis as a result of variable oxidation state?

8. How are nickel and iron used as catalysts in the hydrogenation of alkenes and the Haber process respectively?

9. What are vanadium(V) oxide and manganese(IV) oxide used for in terms of catalytic processes?

10. What are the reactions of Cr³⁺, Fe²⁺, Fe³⁺ and Cu²⁺ with excess aqueous OH?

Last tested: 30/05

Chemical Kinetics

1. What principles underpin the measurement of reaction rate by sampling and quenching?

2. How is reaction order determined from experimental results?

3. What is the general rate equation and how is it used?

4. What is the concept of a rate-determining step?

5. What is the link between reaction kinetics and mechanism?

6. How does the Arrhenius equation show the effect of changing temperature and the use of a catalyst on the rate constant, and how is it used to find the activation energy and frequency factor of a reaction?

   Last tested: 30/05

Enthalpy and Entropy

1. What are the enthalpy changes of atomisation, lattice formation and breaking, hydration and solution?

2. How does the solubility of ionic compounds in water (enthalpy change of solution) depend on the balance between the enthalpy change of lattice breaking and the hydration enthalpies of the ions?

3. What processes are involved in the formation of simple ionic compounds as described in a Born-Haber cycle?

4. How can exothermicity or endothermicity of ΔfH^ϴ serve as a qualitative indicator of a compound’s stability?

5. What is the entropy, S, of a system, and how does it measure the freedom possessed by particles within it?

6. How does the freedom of particles in a solid compare to that in a gas, and how does entropy rank in the sequence of disorder?

7. How can an entropy change be calculated from absolute entropy values?

8. What is the concept of Gibbs free energy change, and how is it calculated?

9. Why do spontaneous reactions have a negative value for ΔG, and how does the effect of entropy change explain the spontaneous occurrence of endothermic processes?

Last tested: 30/05

pH

1. What is the effect of temperature on K_p and K_c for exothermic and endothermic reactions?

2. How can values of K_p and K_c and the quantities presented at equilibrium be calculated from given data?

3. What is the significance of the magnitude of an equilibrium constant and how does this relate to the position of equilibrium?

4. What is the Lowry-Bronsted theory of acids and bases?

5. What are the differences in behaviour between strong and weak acids and bases in terms of the acid dissociation constant, K_a?

6. What is the significance of the ionic product of water, K_w?

7. How can pH, K_w, K_a and pK_a be used in calculations involving strong and weak acids, and pH and K_w in calculations involving strong bases?

8. What are the shapes of the titration curves for strong acid/strong base, strong acid/weak base, weak acid/strong base and weak acid/weak base systems?

9. What is the mode of action of buffer solutions, and how can pH, K_w, K_a and pK_a be used in appropriate calculations?

10. Why are buffer solutions important in living systems and industrial processes?

11. What is the concept of hydrolysis of salts of a strong acid/strong base, a strong acid/weak base and a weak acid/strong base?

12. How is a suitable indicator selected for acid-base titrations?

Last tested: 30/05

59 Total Questions:

Green Aspects - 27 (down from 31)

Yellow Aspects - 18 (down from 20)

Red Aspects - 19 (down from 27)