Advertisements
Advertisements
Question
When BCl3 is treated with water, it hydrolyses and forms [B[OH]4]– only whereas AlCl3 in acidified aqueous solution forms [Al(H2O)6]3+ ion. Explain what is the hybridisation of boron and aluminium in these species?
Advertisements
Solution
\[\ce{BCl3 + 3H2O -> B(OH)3 + 3HCl}\]
\[\ce{B(OH)3 + H2O -> [B(OH)4]– + H+}\]
B(OH)3 due to its incomplete octet accepts an electron pair (as OH–) to give [B(OH)4]–. Boron in this ion involves one 2s orbital and three 2p orbitals. Thus, hybridisation of B in [B(OH)4]– is sp3.
\[\ce{AlCl3 + 6H2O ->[HCl] [Al(H2O)6]^{3+} + 3Cl-}\]
Hence, hybridisation of Al is sp3d2.
APPEARS IN
RELATED QUESTIONS
If B–Cl bond has a dipole moment, explain why BCl3 molecule has zero dipole moment.
How would you explain the lower atomic radius of Ga as compared to Al?
What do you understand by inert pair effect?
The geometry of a complex species can be understood from the knowledge of type of hybridisation of orbitals of central atom. The hybridisation of orbitals of central atom in [Be(OH)4]– and the geometry of the complex are respectively.
Which of the following oxides is acidic in nature?
Ionisation enthalpy (∆iH1kJ mol–1) for the elements of Group 13 follows the order.
In the structure of diborane ______.
Explain why the following compounds behave as Lewis acids?
AlCl3
Aluminium dissolves in mineral acids and aqueous alkalies and thus shows amphoteric character. A piece of aluminium foil is treated with dilute hydrochloric acid or dilute sodium hydroxide solution in a test tube and on bringing a burning matchstick near the mouth of the test tube, a pop sound indicates the evolution of hydrogen gas. The same activity when performed with concentrated nitric acid, reaction doesn’t proceed. Explain the reason.
Explain the following:
PbX2 is more stable than PbX4.
Match the species given in Column I with properties given in Column II.
| Column I | Column II |
| (i) Diborane | (a) Used as a flux for soldering metals |
| (ii) Galluim | (b) Crystalline form of silica |
| (iii) Borax | (c) Banana bonds |
| (iv) Aluminosilicate | (d) Low melting, high boiling, useful for measuring high temperatures |
| (v) Quartz | (e) Used as catalyst in petrochemical industries |
Describe the general trends in the following properties of the elements in Groups 13 and 14.
Metallic character
Describe the general trends in the following properties of the elements in Groups 13 and 14.
Nature of halides
Account for the following observations:
The +1 oxidation state of thallium is more stable than its +3 state.
Three pairs of compounds are given below. Identify that compound in each of the pairs which has group 13 element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.
TlCl3, TlCl
BCl3 exists as monomer whereas AlCl3 is dimerised through halogen bridging. Give reason. Explain the structure of the dimer of AlCl3 also.
Boron fluoride exists as BF3 but boron hydride doesn’t exist as BH3. Give reason. In which form does it exist? Explain its structure.
A group 13 element ‘X’ reacts with chlorine gas to produce a compound XCl3. XCl3 is electron deficient and easily reacts with NH3 to form \[\ce{Cl3X –> NH3}\] adduct; however, XCl3 does not dimerize X is ______.
