Q. 11 B3.7( 17 Votes )
Explain giving reasons:
The enthalpies of atomization of the transition metals are high.
Enthalpies of atomization is the enthalpy change when 1 mol of gaseous atoms is formed from its element in its defined physical state under standard conditions (298.15K, 1 atm). In case of the transition metals enthalpies are high due to high effective nuclear charge and a large number of valence electrons which also leads to strong metallic bonding.
Eg: 515 KJ/mol for for Vanadium,473 KJ/mol for Titanium.
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Mention the type of compounds formed when small atoms like H, C and N gettrapped inside the crystal lattice of transition metals. Also give physical and chemical characteristics of these compounds.Chemistry - Exemplar
(a) Answer the following questions :
(i) Which element of the first transition series has highest second ionization enthalpy?
(ii) Which element of the first transition series has highest third ionization enthalpy?
(iii) Which element of the first transition series has lowest enthalpy of atomisation?
(b) Identify the metal and justify your answer.
(i) Carbonyl M (CO)5
Chemistry - Exemplar
When a chromite ore (A) is fused with sodium carbonate in free excess of air and the product is dissolved in water, a yellow solution of compound (B) is obtained. After treatment of this yellow solution with sulphuric acid, compound (C) can be crystallised from the solution. When compound (C) is treated with KCl solution, orange crystals of compound (D) crystallise out. Identify compounds A to D and also explain the reactions.
An oxide of mangnese (A) is fused with KOH in the presence of an oxidizing agent and dissolved in water. A dark green solution of compound (B) is obtained. Compound (B) disproportionates in neutral or acidic solution to give purple compound (C). Alkaline solution of (C) oxidises potassium iodide solution to a compound (D) and compound (A) is also formed. Identify compounds A to D and also explain the reactions involved.
Chemistry - Exemplar