COMEDK UGET Chemistry - Inorganic Chemistry Flashcards

24 sample cards from the Chemistry - Inorganic Chemistry deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. Why is BeO amphoteric while the oxides of other alkaline earth metals are basic?

   Be is small with high charge density and significant covalent character, so BeO reacts with both acids and bases; the larger metals form purely ionic, basic oxides.

2. What is the cause of Be's anomalous behaviour among alkaline earth metals?

   Its small size, high ionization enthalpy, high electronegativity, absence of d-orbitals, and high charge/size ratio give it largely covalent compounds (diagonal relation with Al).

3. What is gypsum, plaster of Paris, and the reaction connecting them?

   Gypsum is CaSO4.2H2O; heating it to ~393 K gives plaster of Paris, CaSO4.(1/2)H2O, which re-sets to gypsum on adding water.

4. State the inert pair effect and its relevance in Group 13/14.

   The reluctance of the ns2 electrons to participate in bonding, increasing down the group. It makes lower oxidation states more stable (e.g., Tl+ over Tl3+, Pb2+ over Pb4+).

5. Why is BCl3 a Lewis acid while it is electron deficient?

   Boron in BCl3 has only six valence electrons (incomplete octet), so it accepts an electron pair, behaving as a Lewis acid.

6. What are the three allotropes/forms of carbon and a structural feature of each?

   Diamond (sp3, 3D tetrahedral network, hardest), graphite (sp2 layers, conducts, slippery), and fullerene (e.g., C60, cage-like spherical molecule).

7. Why does carbon show catenation more than silicon?

   The C-C bond is much stronger than the Si-Si bond, so carbon forms long, stable chains and rings far more readily than silicon.

8. What are silicones and one of their properties?

   Synthetic organosilicon polymers with (R2SiO)n backbone, made by hydrolysis of alkyl/aryl chlorosilanes. They are water-repellent, thermally stable, and chemically inert.

9. Explain why N2 is exceptionally unreactive.

   N2 has a very strong triple bond (bond dissociation enthalpy ~941 kJ/mol), making it kinetically inert at ordinary temperatures.

10. Why does nitrogen not form pentahalides like phosphorus?

    Nitrogen lacks d-orbitals in its valence shell, so it cannot expand its octet; phosphorus has accessible 3d orbitals and forms PCl5, etc.

11. Describe the structures of the white and red allotropes of phosphorus.

    White phosphorus consists of discrete tetrahedral P4 molecules (reactive, toxic); red phosphorus is a polymeric chain of P4 units (less reactive, stable).

12. State the trend in stability of the +6 and +4 oxidation states down Group 16.

    Stability of +6 decreases and +4 increases down the group due to the inert pair effect (e.g., SO3 vs PoO2).

13. Outline the Contact process for manufacturing sulphuric acid.

    S/SO2 is oxidized to SO3 over V2O5 catalyst (2SO2 + O2 -> 2SO3), SO3 is absorbed in conc. H2SO4 to form oleum (H2S2O7), which is diluted to give H2SO4.

14. Why does ozone act as a powerful oxidizing agent?

    Ozone (O3) readily decomposes to give nascent oxygen (O3 -> O2 + [O]), which is a strong oxidant.

15. State the trend in oxidizing power and bond dissociation enthalpy in Group 17.

    Oxidizing power decreases F2 > Cl2 > Br2 > I2. Bond dissociation enthalpy order: Cl2 > Br2 > F2 > I2 (F2 anomalously low due to small size/lone-pair repulsion).

16. Why is HF a weaker acid than HCl, HBr, and HI?

    The H-F bond is the strongest of the hydrogen halides (small F, high bond enthalpy), so it ionizes least readily, making HF the weakest acid in the series.

17. Why are noble gases (Group 18) chemically inert and which forms most compounds?

    They have stable, completely filled valence shells (ns2np6) and very high ionization enthalpies. Xenon, being largest with lowest IE, forms the most compounds (e.g., XeF2, XeF4, XeF6).

18. Give the hybridization and shape of XeF4.

    sp3d2 hybridization with two lone pairs; square planar shape.

19. Define transition elements and explain why Zn, Cd, Hg are often excluded.

    Elements with partially filled d-orbitals in atom or common ions. Zn, Cd, Hg have completely filled d10 configurations in their common ions, so they are not typical transition metals.

20. Why do transition metals show variable oxidation states?

    Because their (n-1)d and ns orbitals have similar energies, electrons from both can participate in bonding, allowing many oxidation states.

21. Why are most transition metal compounds coloured?

    Due to d-d electronic transitions: an electron absorbs visible light to jump between split d-orbitals, and the complementary colour is observed.

22. State Werner's coordination theory key idea, defining primary and secondary valencies.

    Metals show two valencies: primary valency (ionizable, satisfied by anions, = oxidation state) and secondary valency (non-ionizable, fixed in number, = coordination number, gives geometry).

23. Define ligand, coordination number, and denticity with an example of a bidentate ligand.

    Ligand: an ion/molecule donating an electron pair to the metal. Coordination number: number of donor atoms bonded to the metal. Denticity: number of donor sites; ethylenediamine (en) is bidentate.

24. Name the principal steps in the metallurgical extraction of a metal from its ore.

    Concentration/dressing of ore, conversion to oxide (roasting/calcination), reduction of oxide to metal, and refining/purification of the crude metal.

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