Out of C and CO, which is a better reducing agent at the lower temperature range in the blast furnace to extract iron from the oxide ore?
What happens when
(i) PCl5 is heated?
(ii) H3PO3 is heated?
Write the reactions involved ?
Which metal in the first transition series (3d series) exhibits + 1 oxidation state most frequently and why?
Which of the following cations are coloured in aqueous solutions and why?
Sc3+, V3+, Ti4+, Mn2+ (Atomic number Sc = 21, V = 23, Ti = 22, Mn = 25)
(a) What type of semiconductor is obtained when silicon is doped with boron?
(b) What type of magnetism is shown in the following alignment of magnetic moments?
(c) What type of point defect is produced when AgCl is doped with CdCl2?
Determine the osmotic pressure of a solution prepared by dissolving 2.5 x 10-2 g of K2SO4 in 2L of water at 250C, assuming that it is completely dissociated.
(R = 0.0821 L atm K-1 mol-1, Molar mass of K2SO4 = 174 g mol-1)
How would you account for the following?
(i) Transition metals exhibit variable oxidation states.
(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii.
(iii) Transition metals and their compounds act as catalyst(i) The variable oxidation states of transition elements are due to the participation of ns and (n-1) d-electrons in bonding. Lower oxidation state is exhibited when ns-electrons take part in bonding. Higher oxidation states are exhibited when (n-1) d-electrons take part in bonding.
(ii) This is because the atomic radii of 4d and 5d transition elements are nearly same. This similarity in size is a consequence of lanthanide contraction. Because of this lanthanide contraction, the radii of Hf becomes nearly equal to that of Zr.
(iii) Transition elements act as a good catalyst in chemical reaction because they can lend electrons or withdraw electrons from the reagent, depending on the nature of the reaction. The ability of transition metals to be in a variety of oxidation states, the ability to interchange between the oxidation states and the ability to form complexes with the reagents and be a good source for electrons make transition metals good catalysts.
Write the IUPAC names of the following coordination compounds:
(i) [Cr(NH3)3Cl3]
(ii) K3[Fe(CN)6]
(iii) [CoBr2(en)2]+, (en = ethylenediamine)