Give reasons :
(i) Mn shows the highest oxidation state of +7 with oxygen but with fluorine it shows the highest oxidation state of +4.
(ii) Transition metals show variable oxidation states.
(iii) Actinoids show irregularities in their electronic configurations.
(i) Mn shows the highest oxidation state of +7 with oxygen but with fluorine it shows the highest oxidation state of +4.
(ii) Transition metals show variable oxidation states.
(iii) Actinoids show irregularities in their electronic configurations.
(i) Mn can form pπ -dπ bond with oxygen by using 2p orbital of oxygen and 3d-orbital of Mn because of which it shows highest oxidation state of +7. With fluorine, Mn cannot form pπ – dπ bond thus shows the highest oxidation state of +4.
(ii) Transition metal show variable oxidation state due to comparable energies of ns and (n-1)d orbitals and partially filled d orbitals. So, both these orbitals take part in the reactions.
(iii) Due to comparable energies of 5f, 6d and 7s orbitals and the relative stabilities of f⁰, f⁷ and f¹⁴ occupancies of the 5f orbitals.
(ii) Transition metal show variable oxidation state due to comparable energies of ns and (n-1)d orbitals and partially filled d orbitals. So, both these orbitals take part in the reactions.
(iii) Due to comparable energies of 5f, 6d and 7s orbitals and the relative stabilities of f⁰, f⁷ and f¹⁴ occupancies of the 5f orbitals.
Explain the following :
(i) The enthalpies of atomization of transition metals are quite high.
(ii) The transition metals and many of their compounds act as good catalysts.
Suggest reasons for the following features of transition metal chemistry :
(i) The transition metals and their compounds are usually paramagnetic.
(ii) The transition metals exhibit variable oxidation states.
Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with oxalic acid ?
Write the ionic equations for the reactions.
Write the formula of an oxo-anion of Manganese (Mn) in which it shows the oxidation state equal to its group number.
Explain the following observation :
Most of the transition metal ions exhibit characteristic colour in aqueous solution.
Write the formula of an oxo-anion of Chromium (Cr) in which it shows the oxidation state equal to its group number.
When Cu²⁺ ion is treated with KI, a white precipitate is formed. Explain the reaction with the help of chemical equation.
Account for the following :
(i) CuCl₂ is more stable than Cu₂Cl₂.
(ii) Atomic radii of 4d and 5d series elements are nearly same.
(iii) Hydrochloric acid is not used in permanganate titration.
When a certain conductance cell was filled with 0.1 M KCl, it has a resistance of 85 ohm at 25°C. When the same cell was filled with an aqueous solution of 0.052 M unknown electrolyte, the resistance was 96 ohms. Calculate the molar conductance of the electrolyte at this concentration.
[Specific conductance of 0.1 M KCl = 1.29 × 10⁻² ohm⁻¹ cm⁻¹]
Complete the following reactions—
(i) Cr₂O₇²⁻ + 6Fe²⁺ + 14H⁺ →
(ii) 2CrO₄²⁻ + 2H⁺ →
(iii) 2MnO₄⁻ + 5C₂O₄²⁻ + 16H⁺ →
The molar conductivity of 0.025 mol L⁻¹ methanoic acid is 46.1 S cm² mol⁻¹. Calculate its degree of dissociation and dissociation constant. Given λ°(H⁺) = 349.6 S cm² mol⁻¹ and λ°(HCOO⁻) = 54.6 S cm² mol⁻¹.
(i) Give reasons for the following :
(a) Compounds of transition elements are generally coloured.
(b) MnO is basic while Mn₂O₇ is acidic.
(ii) Calculate the magnetic moment of a divalent ion in aqueous medium if its atomic number is 26.
The electrical resistance of a column of 0.05 M KOH solution of diameter 1 cm and length 45.5 cm is 4.55 × 10³ ohm. Calculate its molar conductivity.
(i) Complete the following equations :
(a) 2MnO₄⁻ + 5SO₃²⁻ + 6H⁺ →
(b) Cr₂O₇²⁻ + 6Fe²⁺ + 14H⁺ →
(ii) Based on the data, arrange Fe²⁺, Mn²⁺ and Cr²⁺ in the increasing order of stability of +2 oxidation state.
E°(Cr³⁺/Cr²⁺) = -0.4 V
E°(Mn³⁺/Mn²⁺) = +1.5 V
E°(Fe³⁺/Fe²⁺) = + 0.8 V