Advertisements
Advertisements
प्रश्न
On the basis of the figure given below, answer the following questions:
- Why Manganese has lower melting point than Chromium?
- Why do transition metals of 3d series have lower melting points as compared to 4d series?
- In the third transition series, identify and name the metal with the highest melting point.
Advertisements
उत्तर
- Manganese is having lower melting point as compared to chromium, as it has highest number of unpaired electrons, strong interatomic metal bonding, hence no delocalisation of electrons.
- There is much more frequent metal-metal bonding in compounds of the heavy transition metals i.e 4d and 5d series, which accounts for lower melting point of 3d series.
- Tungsten
APPEARS IN
संबंधित प्रश्न
Why do interstitial compounds have higher melting points than corresponding pure metals?
Account for the following:
Cr2+ is a strong reducing agent.
How would you account for the following: Transition metals form complex compounds.
A solution of \[\ce{KMnO4}\] on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out?
Answer the following question:
Which element of the first transition series has highest third ionisation enthalpy?
Identify the metal and justify your answer.
Carbonyl \[\ce{M(CO)5}\]
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.
Account for the following:
In case of transition elements, ions of the same charge in a given series show progressive decrease in radius with increasing atomic number.
Give reason for the following statement:
[Ti(H2O)]3+ is coloured while [Sc(H2O)6]3+ is colourless.
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.
