Explain the following observations:
(i) Copper atom has completely filled d orbitals (3d¹⁰) in its ground state, yet it is regarded as a transition element.
(ii) Cr²⁺ is a stronger reducing agent than Fe²⁺ in aqueous solution.
(i) Copper atom has completely filled d orbitals (3d¹⁰) in its ground state, yet it is regarded as a transition element.
(ii) Cr²⁺ is a stronger reducing agent than Fe²⁺ in aqueous solution.
(i) Because it has incompletely filled d orbitals in one of its oxidation state (Cu²⁺).
(ii) Cr²⁺ (d⁴) changes to Cr³⁺ (d³) while Fe²⁺ (d⁶) changes to Fe³⁺ (d⁵). In aqueous medium d³ is more stable than d⁵ .
(ii) Cr²⁺ (d⁴) changes to Cr³⁺ (d³) while Fe²⁺ (d⁶) changes to Fe³⁺ (d⁵). In aqueous medium d³ is more stable than d⁵ .
Explain the following observation :
(i) Silver atom has completely filled d-orbitals (4d¹⁰) in its ground state, yet it is regarded as a transition element.
(ii) E° value for the Mn³⁺/Mn²⁺ couple is much more positive than Cr³⁺/Cr²⁺
Explain the following observation :
Most of the transition metal ions exhibit characteristic colour in aqueous solution.
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.
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.
What is meant by ‘disproportionation’ ? Give an example of a disproportionation reaction in aqueous solution.
Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with (i) an iodide (ii) H₂S.
Assign the reason for the following :
Copper (I) ion is not known in aqueous solution.
What are the transition elements ? Write two characteristics of the transition elements.
How many electrons flow when a current of 5 amps is passed through a solution for 193 sec ? Given F = 96500 C. \(N_0\) = 6.002 × \(10^{23}\) \(mol^{-1}\).
What is meant by ‘disproportionation’ ? Give an example of a disproportionation reaction in aqueous solution.
In the following ions:
Mn³⁺, V³⁺, Cr³⁺, Ti⁴⁺
(Atomic no: Mn = 25, V = 23, Cr = 24, Ti = 22)
(a) Which ion is most stable in an aqueous solution?
(b) Which ion is the strongest oxidizing agent?
(c) Which ion is colourless?
(d) Which ion has the highest number of unpaired electrons?
(i) Following reactions occur at cathode during the electrolysis of aqueous silver chloride solution :
= +0.80 V
= 0.00 V
On the basis of their standard reduction electrode potential (E°) values, which reaction is feasible at the cathode and why ?
(ii) Define limiting molar conductivity. Why conductivity of an electrolyte solution decreases with the decrease in concentration ?