Ncert Solutions Chemistry Class 11th
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10.21. Describe the importance of the following:
(i) Limestone (ii) Cement (iii) Plaster of paris.
10.21. Describe the importance of the following:
(i) Limestone (ii) Cement (iii) Plaster of paris.
Limestone:
- A raw material for cement.
- It is used as a building material in the form ofmarble and in the manufacture of quick lime.
- used in the manufactureof high quality paper. It is also used as anantacid, mildabrasive in tooth paste, aconstituent of chewing gum, and a filler incosmetics.
Cement:
- It is
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10.20. The hydroxides and carbonates of sodium and potassium are easily soluble in water while the corresponding salts of magnesium and calcium are sparingly soluble in water. Explain.
10.20. The hydroxides and carbonates of sodium and potassium are easily soluble in water while the corresponding salts of magnesium and calcium are sparingly soluble in water. Explain.
Since group 1 hydroxides and carbonates due to large size contain higher hydration energy than the lattice energy so, they are easily soluble in water. Whereas, in magnesium and calcium due to small size their lattice energy dominates over hydration energy they are sparingly soluble in water.
Upvote 10.19. Draw the structure of (i) BeCl2 (vapour), (ii) BeCl2 (solid).
10.19. Draw the structure of (i) BeCl2 (vapour), (ii) BeCl2 (solid).
BeCl2 (vapour)
In the vapour state, it exists as a chloro-bridged dimer.
Upvote 10.18. Describe two important uses of each of the following:
(i) caustic soda (ii) sodium carbonate (iii) quicklime.
10.18. Describe two important uses of each of the following:
(i) caustic soda (ii) sodium carbonate (iii) quicklime.
(i) Caustic soda
It is used in (a) the manufacture of soap, paper, artificial silk and a number of chemicals, (b) in petroleum refining, (c) in the purification of bauxite, (d) in the textile industries for mercerising cotton fabrics, (e) for the preparation of pure fats and oils, and (f) as a labor
Upvote 10.17. What happens when (i) magnesium is burnt in air, (ii) quick lime is heated with silica (iii) chlorine reacts with slaked lime (iv) calcium nitrate is heated?
10.17. What happens when (i) magnesium is burnt in air, (ii) quick lime is heated with silica (iii) chlorine reacts with slaked lime (iv) calcium nitrate is heated?
(i) Magnesium is burnt in air to form magnesium oxide and magnesium nitride.
2Mg + O2 → 2MgO
3Mg + N2 → Mg3N2.
(ii) Quick lime is heated with silica above 1273 K to obtain calcium silicate
CaO+SiO2 → CaSiO3.
(iii) Chlorine reacts with slaked lime to form calcium hypochlorite- a constituent
Upvote 10.16. Starting with sodium chloride how would you proceed to prepare
(i) Sodium metal
(ii) Sodium hydroxide
(iii) Sodium peroxide
(iv) Sodium carbonate?
10.16. Starting with sodium chloride how would you proceed to prepare
(i) Sodium metal
(ii) Sodium hydroxide
(iii) Sodium peroxide
(iv) Sodium carbonate?
(i) Sodium metal is manufactured by electrolysis of a fused mass of NaCl 40% and CaCl2 60% in Down’s cell at 873 K, using iron as cathode and graphite as anode. Na is liberated at the cathode.
At cathode:
Na+ + e– → Na (l)
At anode:
2Cl– (melt) → Cl2 (g) + 2e–.
(ii) Sodium hy
Upvote 10.15. 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.
10.15. 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.
(a) Nitrates of both group 1 and group 2 elements are soluble in water because hydration energy is more than the lattice energy.
Nitrates of both group 1 and group 2 elements are thermally unstable but they decompose differently except LiCO3 e.g.
2NaNO3 →2NaNO2 + O2
2KNO3 →2KNO2 + O2
4LiNO3 →
Upvote 10.14. Why is Li2CO3 decomposed at a lower temperature whereas Na2CO3 at higher temperature?
10.14. Why is Li2CO3 decomposed at a lower temperature whereas Na2CO3 at higher temperature?
Li2CO3 is a covalent compound whereas Na2CO3 is an ionic compound. Therefore, lattice energy of Na2CO3 is higher than that of Li2CO3. Thus, LiCO3 is decomposed at a lower temperature as compared to Na2CO3.
Upvote 10.13. Potassium carbonate cannot be prepared by Solvay process. Why?
10.13. Potassium carbonate cannot be prepared by Solvay process. Why?
Potassium carbonate cannot be prepared by Solvay process because potassium hydrogencarbonate is too soluble to be precipitated by the addition of ammonium hydrogencarbonate to a saturated solution of potassium chloride.
Upvote 10.12. Discuss the various reactions that occur in the Solvay process.
10.12. Discuss the various reactions that occur in the Solvay process.
Solvay process is also known as ammonia soda process, wherein carbon dioxide is passed through a brine solution (containing about 28 % NaCl) which is saturated with ammonia to form sodium carbonate.
2NH3 + H2O + CO2 → (NH4)2CO3
(NH4)2CO3 + H2O + CO2 → 2NH4HCO3
NH4HCO3 + NaCl → NaHCO3↓ + NH4Cl
The precip
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