Class 11 Chemistry - Chapter The s Block Elements NCERT Solutions | How would you explain the following obse
How would you explain the following observations?
(i) BeO is almost insoluble but BeSO4 in soluble in water,
(ii) BaO is soluble but BaSO4 is insoluble in water,
(iii) LiI is more soluble than KI in ethanol.
(i) BeO is almost insoluble in water and BeSO4 is soluble in water. Be2+ is a small cation with a high polarizing power and O2- is a small anion. The size compatibility of Be2+ and O2- is high. Therefore, the lattice energy released during their formation is also very high. When BeO is dissolved in water, the hydration energy of its ions is not sufficient to overcome the high lattice energy. Therefore, BeO is insoluble in water. On the other hand, SO2-4 ion is a large anion. Hence, Be2+ can easily polarize SO2-4 ions, making BeSO4 unstable. Thus, the lattice energy of BeSO4 is not very high and so it is soluble in water.
(ii) BaO is soluble in water, but BaSO4 is not. Ba2+ is a large cation and O2- is a small anion. The size compatibility of Ba2+ and O2- is not high. As a result, BaO is unstable. The lattice energy released during its formation is also not very large. It can easily be overcome by the hydration energy of the ions. Therefore, BaO is soluble in water. In BaSO4, Ba2+ and SO2-4 are both large-sized. The lattice energy released is high. Hence, it is not soluble in water.
(iii) Lil is more soluble than KI in ethanol. As a result of its small size, the lithium ion has a higher polarizing power than the potassium ion. It polarizes the electron cloud of the iodide ion to a much greater extent than the potassium ion. This causes a greater covalent character in LiI than in KI. Hence, LiI is more soluble in ethanol.
More Questions From Class 11 Chemistry - Chapter The s Block Elements
- Q:-
Compare the alkali metals and alkaline earth metals with respect to
(i) ionization enthalpy
(ii) basicity of oxides and
(iii) solubility of hydroxides.
- Q:-
Compare the solubility and thermal stability of the following compounds of the alkali metals with those of the alkaline earth metals.
(a) Nitrates (b) Carbonates (c) Sulphates.
- Q:-
Discuss the various reactions that occur in the Solvay process.
- Q:-
Comment on each of the following observations:
(a) The mobilities of the alkali metal ions in aqueous solution are Li+ < Na+ < K+ < Rb+ < Cs+
(b) Lithium is the only alkali metal to form a nitride directly.
(c) E° for M2+(aq) (where M = Ca, Sr or Ba) is nearly constant.
- Q:-
Why are lithium salts commonly hydrated and those of the other alkali metal ions usually anhydrous?
- Q:-
State as to why
(a) a solution of Na2CO3 is alkaline ?
(b) alkali metals are prepared by electrolysis of their fused chlorides ?
(c) sodium is found to be more useful than potassium ?
- Q:-
When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change.
- Q:-
Why is Li2CO3 decomposed at a lower temperature whereas Na2CO3 at higher temperature?
- Q:-
In what ways lithium shows similarities to magnesium in its chemical behaviour?
- Q:-
Find the oxidation state of sodium in Na2O2.
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(iv) whose value depends on temperature only. - Q:-
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