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 why :
(i) E° for Mn³⁺/Mn²⁺ couple is more positive than that for Fe³⁺/Fe²⁺. (At. Nos. Mn = 25, Fe = 26).
(ii) Ce³⁺ can be easily oxidized to Ce⁴⁺. (At. No.Ce = 58).
Name the following :
(i) A transition metal which does not exhibit variation in oxidation state in its compounds.
(ii) A compound where the transition metal is in the +7 oxidation state.
(iii) A member of the lanthanoid series which is well known to exhibit +4 oxidation state.
(iv) Ore used in the preparation of Potassium dichromate.
When chromite ore FeCr₂O₄ is fused with NaOH in presence of air, a yellow coloured compound
(A) is obtained which on acidification with dilute sulphuric acid gives a compound (B). Compound (B) on reaction with KCl forms a orange coloured crystalline compound (C).
(i) Write the formulae of the compounds (A), (B) and (C).
(ii) Write one use of compound (C).
Complete and balance the following chemical equations:
(a) Fe²⁺ + MnO₄⁻ + H⁺ →
(b) MnO₄⁻ + H₂O + I⁻ →
Complete the following chemical equations :
(i) MnO₄⁻(aq) + S₂O₃²⁻(aq) + H₂O(l) →
(ii) Cr₂O₇²⁻(aq) + Fe²⁺(aq) + H⁺(aq) →
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.
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?
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.
What are the transition elements ? Write two characteristics of the transition elements.
What is meant by ‘disproportionation’ ? Give an example of a disproportionation reaction in aqueous solution.
The partial pressure of ethane over a saturated solution containing 6.56 × 10⁻² g of ethane is 1 bar. If the solution were to contain 5.0 × 10⁻² g of ethane, then what will be the partial pressure of the gas ?
Calculate the molality of ethanol solution in which the mole fraction of water is 0.88.
Define the following terms :
(i) Mole fraction (x)
(ii) Molality of a solution (m)
State Henry’s law and mention two of its important applications.