Explain Why Questions in Transition Elements - Inorganic chemistry questions and answers (Part 2)
Explain Why Questions in Transition Elements - Inorganic chemistry questions and answers (Part 2)
1.
Sc dissolves in NaOH.
Answer:
Because Sc is amphoteric
and can dissolve in bases like NaOH
2.
(+III) oxidation state of group IIIB
elements do not have strong tendency to form complexes.
Answer:
Because of their large
size that smaller elements complex better than large elements.
3.
Sc from complexes more than group IIB
elements.
Answer:
Due to its small size.
4.
The metals of group IIIB are
difficult to separate
Answer:
Due to their high melting
point, also they react with water and their oxides are stable so that thermite
reaction cannot be used
5.
Actinium is rare to found.
Answer:
Because Actinium found in
two isotopes, which are both intensely radioactive with half-life periods of 6
hours and 22 years so that any actinium present when earth was formed will have
long decayed.
6.
Lanthanum salts are used as
biological tracer.
Answer:
This because La3+ appears
to replace Ca2+ in conduction of nerve impulses along the axon of
nerve cells, and in structure promoting in cell membrane, this because La3+
and Ca2+ are similar in size and La3+ is readily detected
by electron spin resonance
7.
TI3+ is
more reducing than Sn2+ or (+III) oxidation state of group
IVB is reducing.
Answer:
Because (+III) oxidation state of
titanium group is relatively unstable and the elements of this group have high
tendency to +IV oxidation state, so they act as reducing agents to reach the
most stable (+IV) state
8.
The compounds of oxidation state
(+II) of group IVB are strong reducing agents that they reduce water.
Answer:
Because (+II) oxidation
state of titanium group is very unstable and the elements of this group have
high tendency to (+IV) oxidation state so they act as strong reducing agents to
reach the most stable (+IV) state.
9.
Hf and Zr have similar chemical
properties or Separartion of Zr and Hf is difficult.
Answer:
Because the expected
increase in size from Zr to Hf is cancelled by the decrease in size because of
filling of the 4f level (lanthanide contraction) so they have similar size and
properties.
10. The metals of
group IVB are passive or unreactive at room temperature.
Answer:
Due to the formation of
thin impermeable oxide film on the metal surface, so they are unaffected by
acids or alkalis at room temperature.
11. TiO2 is better than white
lead in use as a white pigment in paint.
Answer:
Because TiO2 is nontoxic
12. Ti4+ ions is not found in
solution
Answer:
Because the charge/radius ratio is too high
13.The reaction of TiO2 with
acids does not give Ti4+ ions in solution.
Answer:
Because
the charge/radius ratio is too high, and basic salts are formed
Answer:
Because
on strong heating ZrO2 becomes very hard and its high melting point
of 2700 °C and resistance to chemical attack make it useful for making high
temperature crucibles and furnace linings.
15. Zr4+ ions are not found in
solution
Answer:
Because the charge/radius ratio is too high
16. ZrOCl2 is used in
qualitative analysis to remove any phosphate present which would interfere with
the analysis of metals.
Answer:
Because ZrOCl2 contains the ion [Zr4
(OH)8(H2O)16]8+. This is used in
qualitative analysis to remove any phosphate present which would interfere with
the analysis of metals since zirconium phosphate is insoluble.
17.Ti(IV) solutions can be used for the
colorimetric determination of H2O2 (hydrogen peroxide)
Answer:
Because Ti (IV) solutions form an intense
yellow-orange color with of H2O2 this can be used for the
colorimetric determination of H2O2
18.
ZrCl4 hydrolysis in water is incomplete
Answer:
Because
the zirconium oxychloride is stable
19.
All the (+III) compounds of group IVB are colored.
Answer:
Because all the (+III) compounds have a d1
configuration and are colored and paramagnetic.
20. TiX3 compounds in water yields
two complexes with different colors which then disproportionate to TiX2 and TiX4
Answer:
The different colors because the six ligands
may be either six water molecules, or five water molecules and one chloride
ion. This give different crystal field splitting of the d level
21. Zr
and Hf found only a solid
Answer:
Because Zr and Hf are unstable in
water
22.Hf occurs in zirconium ores and they
are difficult to separate.
Answer:
Because Hafnium is very similar to zirconium because
of lanthanide contraction.
23.Ti
metal is not easy to extract
Answer:
Because
of its high melting point and because it reacts readily with air, oxygen, nitrogen
carbon and hydrogen at elevated temperatures
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