Advertisements
Advertisements
प्रश्न
What are interstitial compounds?
What are interstitial compounds? Why do these compounds have higher melting points than corresponding pure metals?
Advertisements
उत्तर
- Interstitial compounds are those which are formed when small atoms like H, C, N, B, etc. are trapped inside the crystal lattice of metals.
- They have a higher melting point than metals because the metal-nonmetal bonds are stronger than the metal-metal bonds in pure metals.
- They are usually non-stoichiometric and are neither typically ionic nor covalent; for example, TiC, Mn4N, Fe3H, VH0.56, and TiH1.7.
संबंधित प्रश्न
Which of the following cations are coloured in aqueous solutions and why ?
Sc3+, V3+, Ti4+, Mn2+ (At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25)
Why +2 oxidation state of manganese is more stable?
Account for the following:
Cu+2 salts are coloured, while Zn2+ salts are white.
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element has the highest m.p?
How would you account for the following: Transition metals form complex compounds.
Give reasons:
Transition metals show variable oxidation states.
How would you account for the following : Transition metals form coloured compounds
In the series Sc (Z = 21) to Zn (Z = 30), the enthalpy of atomization of zinc is the lowest, i.e., 126 kJ mol−1. Why?
Which of the d-block elements may not be regarded as the transition elements?
Predict which of the following will be coloured in the aqueous solution?
Ti3+, V3+, Cu+, Sc3+, Mn2+, Fe3+ and Co2+. Give reasons for each.
How would you account for the following:
Of the d4 species, Cr2+ is strongly reducing while manganese (III) is strongly oxidising.
Which metal in the first series of transition metals exhibits +1 oxidation state most frequently and why?
An antifriction alloy made up of antimony with tin and copper, which is extensively used in machine bearings is called _______.
(A) Duralumin
(B) Babbitt metal
(C) Spiegeleisen
(D) Amalgam
NF3 is possible, but NF5 is not. Why?
Following are the transition metal ions of 3d series:
Ti4+, V2+, Mn3+, Cr3+
(Atomic numbers: Ti = 22, V = 23, Mn = 25, Cr = 24)
Answer the following:
1) Which ion is most stable in an aqueous solution and why?
2) Which ion is a strong oxidising agent and why?
3) Which ion is colourless and why?
Give reasons Iron has the higher enthalpy of atomization than that of copper.
Why does the density of transition elements increase from Titanium to Copper? (at. no. Ti = 22, Cu = 29)
The paramagnetic character in the 3d-transition series elements increases up to Mn and then decreases.
How is potassium dichromate prepared from chrome iron ore?
Explain why transition metals and their compounds act as a catalyst.
\[\ce{KMnO4}\] acts as an oxidising agent in acidic medium. The number of moles of \[\ce{KMnO4}\] that will be needed to react with one mole of sulphide ions in acidic solution is ______.
Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?
When acidified \[\ce{K2Cr2O7}\] solution is added to \[\ce{Sn^{2+}}\] salts then \[\ce{Sn^{2+}}\] changes to ______.
Transition elements show high melting points. Why?
Match the solutions given in Column I and the colours given in Column II.
| Column I (Aqueous solution of salt) |
Column II (Colour) |
| (i) \[\ce{FeSO2.7H2O}\] | (a) Green |
| (ii) \[\ce{NiCl2.4H2O}\] | (b) Light pink |
| (iii) \[\ce{MnCl2.4H2O}\] | (c) Blue |
| (iv) \[\ce{CoC12,6H2O}\] | (d) Pale green |
| (v) \[\ce{Cu2 Cl2}\] | (e) Pink |
| (f) Colourless |
Assertion: Separation of \[\ce{Zr}\] and \[\ce{Hf}\] is difficult.
Reason: Because \[\ce{Zr}\] and \[\ce{Hf}\] lie in the same group of the periodic table.
Identify A to E and also explain the reactions involved.
Answer the following question:
Which element of the first transition series has lowest enthalpy of atomisation?
Identify the metal and justify your answer.
\[\ce{MO3F}\]
A metallic ion 'M' reacts with chloride ion to form white precipitate which is readily soluble in aqueous ammonia. Identify 'M'?
The element with atomic number 46 belongs to
If enthalpies of formation of C2H4(g), CO2(g) and H2O(l) at 25°C and 1 atm pressure are 52, – 394 and – 286 kJ/mol respectively, the change in ethalpy for combustion of C2H4 is equal to
On strong heating AgNO3, the gases evolved are:-
Photographic film and plates have - au essential ingredient of
Mercury is the only metal liquid at room temperature due to its:-
The complex showing a spin-span magnetic moment of 2.82 B.M. is :-
Which one of the following characters tie of the transition metal is associated with higher catalytic activity?
Give reasons for the following statement:
Zn, Cd, and Hg are soft metals.
Why Zn, Cd and Hg are not called transition metals?
The disproportionation of \[\ce{MnO^{2-}_4}\] in acidic medium resulted in the formation of two manganese compounds A and B. If the oxidation state of Mn in B is smaller than that of A, then the spin-only magnetic moment (µ) value of B in BM is ______. (Nearest integer)
Assertion (A): Transition metals have high enthalpy of atomisation.
Reason (R): Greater number of unpaired electrons in transition metals results in weak metallic bonding.
Complete the following reaction and justify that it is a disproportionation reaction:
\[\ce{3MnO^{2-}4 + 4H^+ -> \underline{}\underline{}\underline{}\underline{} + \underline{}\underline{}\underline{}\underline{} + 2H2O}\]
Account for the following:
Copper has an exceptionally positive `"E"_("M"^(2+)//"M")^0` value.
In order to protect iron from corrosion, which one will you prefer as a sacrificial electrode, Ni or Zn? Why? (Given standard electrode potentials of Ni, Fe and Zn are -0.25 V, -0.44 V and -0.76 V respectively.)
A pair of coloured ions is ______.
Explain the magnetic properties of d-block (or transition) elements.
Explain the use of different transition metals as catalysts.
