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.
(i) The transition metals and their compounds are usually paramagnetic.
(ii) The transition metals exhibit variable oxidation states.
(i) Due to presence of unpaired electrons in d-orbitals.
(ii) Due to incomplete filling of d-orbitals. Due to very small energy difference in between (n-1) d and n s-orbitals.
(ii) Due to incomplete filling of d-orbitals. Due to very small energy difference in between (n-1) d and n s-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.
Explain the following observation :
Most of the transition metal ions exhibit characteristic colour in aqueous solution.
How would you account for the following ? Many of the transition elements are known to form interstitial compounds.
What are the transition elements ? Write two characteristics of the transition elements.
(i) Account for the following :
(a) Cu⁺ is unstable in an aqueous solution.
(b) Transition metals form complex compounds.
(ii) Complete the following equation :
CrO₂₇²⁻ + 8H⁺ + 3NO₂⁻ →
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.
Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with (i) an iodide (ii) H₂S.
The conductivity of metals decreases while that of electrolytes increases with increase in temperature. Why?
(i) State the law which helps to determine the limiting molar conductivity of weak electrolyte.
(ii) Calculate limiting molar conductivity of CaSO₄ (limiting molar conductivity of calcium and sulphate ions are 119.0 and 160.0 Scm² mol⁻¹ respectively)
Complete and balance the following chemical equations:
(a) Fe²⁺ + MnO₄⁻ + H⁺ →
(b) MnO₄⁻ + H₂O + I⁻ →
(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 ?
Define the following terms :
(i) Fuel cell
(ii) Limiting molar conductivity