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प्रश्न
Why do interstitial compounds have higher melting points than corresponding pure metals?
उत्तर
The melting points of interstitial compounds are higher than those of pure metals because of bonding between the metal and the non-metal, which is stronger than metal–metal bonding.
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संबंधित प्रश्न
Which metal in the first transition series (3d series) exhibits + 1 oxidation state most frequently and why?
ln which pair highest oxidation states of transition metals are found:
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?
Account for the following:
Cu+ ion is unstable in aqueous solution.
|
`E_((M^(2+)/M)` |
Cr | Mn | Fe | Co | Ni | Cu |
| -0.91 | -1.18 | -0.44 | -0.28 | -0.25 | -0.34 |
From the given data of E0 values, answer the following questions :
(1) Why is `E_(((Cu^(2+))/(Cu)))` value exceptionally positive
(2) Why is `E_(((Mn^(2+))/(Mn)))` value is highly negative as compared to other elements
(3) Which is the stronger reducing agents Cr2+ or Fe2+ ? Give Reason.
How would you account for the irregular variation of ionization enthalpies (first and second) in the first series of the transition elements?
Calculate the ‘spin only’ magnetic moment of \[\ce{M^{2+}_{ (aq)}}\] ion (Z = 27).
How would you account for the following:
Of the d4 species, Cr2+ is strongly reducing while manganese (III) is strongly oxidising.
How would you account for the following:
The d1 configuration is very unstable in ions.
Write down the number of 3d electrons in the following ion:
Cu2+
Indicate how would you expect the five 3d orbitals to be occupied for this hydrated ions (octahedral).
How would you account for the following?
Zr (Z = 40) and Hf (Z = 72) have almost identical radii.
Complete and balance the following chemical equations
`MnO_4^(-) + H_2O + I^(-) ->`
Dissociation of H2S is suppressed in acidic medium.
Explain why:
(i) Mn2+ is more stable than Fe2+ towards oxidation to +3 state.
(At. no. of Mn = 25, Fe = 26)
(ii) Transition elements usually form coloured ions.
(iii) Zr and Hf exhibit similar properties.
(At. no. of Zr = 40, Hf = 72)
Why EΘ values for Mn, Ni and Zn are more negative than expected?
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 |
Answer the following question:
Which element of the first transition series has lowest enthalpy of atomisation?
A violet compound of manganese (A) decomposes on heating to liberate oxygen and compounds (B) and (C) of manganese are formed. Compound (C) reacts with KOH in the presence of potassium nitrate to give compound (B). On heating compound (C) with conc. \[\ce{H2SO4}\] and \[\ce{NaCl}\], chlorine gas is liberated and a compound (D) of manganese along with other products is formed. Identify compounds A to D and also explain the reactions involved.
Which of the following species has maximum magnetic momentum?
Agcl is soluble in NH4OH. The solubility is due to the information of:-
Which of the following ions has the maximum magnetic moment?
Consider the following standard electrode potentials (E° in volts) in aqueous solution:
| Element | M3+/M | M+/M |
| Al | - 1.66 | +0.55 |
| Tl | + 1.26 | -0.34 |
Based on these data, which of the following statements is correct?
The oxidation state of Fe in [Fe(CO)5] is ______.
Which of the following ions has the electronic configuration 3d6?
(Atomic number: Mn = 25, Co = 27, Ni = 28)
What is the oxidation state of chromium in chromate ion and dichromate ion?
Explain the use of different transition metals as catalysts.
For M2+/M and M3+/M2+systems, the EΘ 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 ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
