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प्रश्न
What are interstitial compounds?
What are interstitial compounds? Why do these compounds have higher melting points than corresponding pure metals?
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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 metal in the first transition series (3d series) exhibits + 1 oxidation state most frequently and why?
Complete the following chemical equations:
`(i) Cr_2O_7^(2-)+6Fe^(2+)+14H^+ ->`
`(ii) 2CrO_4^(2-)+2H^+ ->`
`(iii) 2MnO_4^-+5C_2O_4^(2-)+16H^+ ->`
Account for the following:
Cu+2 salts are coloured, while Zn2+ salts are white.
Account for the following:
Zn is not considered as a transition element.
Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?
Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?
How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
For M2+/M and M3+/M2+ systems, the E° values for some metals are as follows:
| Cr2+/Cr | −0.9 V |
| Mn2+/Mn | −1.2 V |
| Fe2+/Fe | −0.4 V |
| Cr3/Cr2+ | −0.4 V |
| Mn3+/Mn2+ | +1.5 V |
| Fe3+/Fe2+ | +0.8 V |
Use this data to comment upon:
- The stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+ and
- the ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
Predict which of the following will be coloured in the aqueous solution?
Ti3+, V3+, Cu+, Sc3+, Mn2+, Fe3+ and Co2+. Give reasons for each.
Compare the stability of +2 oxidation state for the elements of the first transition series.
Which metal in the first series of transition metals exhibits +1 oxidation state most frequently and why?
What are alloys?
What are inner transition elements?
How would you account for the following?
Transition metals and their compounds act as catalysts.
An analysis shows that FeO has a non-stoichiometric composition with formula Fe0.95O. Give reason.
How is potassium dichromate prepared from chrome iron ore?
Explain why Zn2+ salts are white whereas Cu2+ salts are coloured.
Give reasons for the following:
The transition metals generally form coloured compounds.
Which among the following transition metal has the lowest melting point?
Transition metals with lowest melting point is ______.
When \[\ce{KMnO4}\] solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because ______.
\[\ce{KMnO4}\] 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?
Which of the following ions show higher spin only magnetic moment value?
(i) \[\ce{Ti^3+}\]
(ii) \[\ce{Mn2+}\]
(iii) \[\ce{Fe2+}\]
(iv) \[\ce{Co3+}\]
Transition elements form binary compounds with halogens. Which of the following elements will form \[\ce{MF3}\] type compounds?
(i) \[\ce{Cr}\]
(ii) \[\ce{Co}\]
(iii) \[\ce{Cu}\]
(iv) \[\ce{Ni}\]
Why does copper not replace hydrogen from acids?
While filling up of electrons in the atomic orbitals, the 4s orbital is filled before the 3d orbital but reverse happens during the ionisation of the atom. Explain why?
Match the catalysts given in Column I with the processes given in Column II.
| Column I (Catalyst) | Column II (Process) |
| (i) \[\ce{Ni}\] in the presence of hydrogen | (a) Zieglar Natta catalyst |
| (ii) \[\ce{Cu2C12}\] | (b) Contact process |
| (iii) \[\ce{V2O5}\] | (c) Vegetable oil to ghee |
| (iv) Finely divided iron | (d) Sandmeyer reaction |
| (v) \[\ce{TiCl4 + Al (CH3)3}\] | (e) Haber's Process |
| (f) Decomposition of KCIO3 |
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 |
Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:
(activation energy, Threshold energy, increased, lowered, partially, full, d-d transition, Benzoic acid, benzaldehyde)
Only those transition metal ions will be coloured which have ______ filled d-orbitals facilitating ______.
Photographic film and plates have - au essential ingredient of
Mercury is the only metal liquid at room temperature due to its:-
The basic character of transition metals monoxide follow the order.
Agcl is soluble in NH4OH. The solubility is due to the information of:-
Which of the following ions will exhibit colour in aqueous solution?
Which of the following transition metal is not coloured?
Why are all copper halides known except that copper iodide?
Give reason for the following statement:
[Ti(H2O)]3+ is coloured while [Sc(H2O)6]3+ is colourless.
Account for the following:
Sc3+ is colourless whereas Ti3+ is coloured in an aqueous solution.
Account for the following:
Ce4+ is a strong oxidising agent.
Which property of transition metals enables them to behave as catalysts?
Consider the following standard electrode potential values:
\[\ce{Sn^{2+}_{ (aq)} + 2e^- -> Sn_{(s)}}\]; E0 = −0.14 V
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\]; E0 = +0.77 V
What is the cell reaction and potential for the spontaneous reaction that occurs?
Give a reason for the following:
Transition metals possess a great tendency to form complex compounds.
Give a reason for the following.
Some transition metals and their compounds get attracted towards the magnetic field.
The E° value for the Mn2+/Mn2+ couple is more positive than that of Cr3+/Cr2+ or Fe3+/Fe2+ due to the change of:
‘Spin only’ magnetic moment is the same for which of the following ions?
- Ti3+
- Cr2+
- Mn2+
- Fe2+
- Sc3+
Choose the most appropriate answer from the options given below:
