Class 11 Chemistry - Chapter Hydrogen NCERT Solutions | Discuss the principle and method of soft
Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.
The process of treating permanent hardness of water using synthetic resins is based on the exchange of cations (e.g., Na+, Ca2+, Mg2+ etc) and anions (e.g., Cl-, SO2-4, HCO-3 etc) present in water by H+ and OH- ions respectively.
Synthetic resins are of two types:
1) Cation exchange resins
2) Anion exchange resins
Cation exchange resins are large organic molecules that contain the -SO3H group. The resin is firstly changed to RNa (from RSO3H) by treating it with NaCl. This resin then exchanges Na+ ions with Ca2+ and Mg2+ ions, thereby making the water soft.
2RNa + M2+ (aq) → R2M(s) + 2Na + (aq)
There are cation exchange resins in H+ form. The resins exchange H+ ions for Na+, Ca2+, and Mg2+ ions.
Anion exchange resins exchange OH- ions for anions like Cl-,HCO-3, and SO42- present in water.
During the complete process, water first passes through the cation exchange process. The water obtained after this process is free from mineral cations and is acidic in nature.
This acidic water is then passed through the anion exchange process where OH- ions neutralize the H+ ions and de-ionize the water obtained.
More Questions From Class 11 Chemistry - Chapter Hydrogen
- Q:-
Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.
- Q:-
Compare the structures of H2O and H2O2.
- Q:-
Write chemical reactions to show the amphoteric nature of water.
- Q:-
Arrange the following
(i) CaH2, BeH2 and TiH2 in order of increasing electrical conductance.
(ii) LiH, NaH and CsH in order of increasing ionic character.
(iii) H-H, D-D and F-F in order of increasing bond dissociation enthalpy.
(iv) NaH, MgH2 and H2O in order of increasing reducing property.
- Q:-
What do you understand by the term “non-stoichiometric hydrides”? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.
- Q:-
What is meant by 'demineralised' water and how can it be obtained?
- Q:-
What causes the temporary and permanent hardness of water?
- Q:-
How does H2O2 behave as a bleaching agent?
- Q:-
Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?
- Q:-
Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?
Popular Questions of Class 11 Chemistry
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How do you account for the formation of ethane during chlorination of methane?
- Q:-
What are hybridisation states of each carbon atom in the following compounds ?
(i) CH2=C=O,
(ii) CH3CH=CH2,
(iii) (CH3)2CO,
(iv) CH2=CHCN,
(v) C6H6
- Q:-
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
- Q:-
What are the common physical and chemical features of alkali metals?
- Q:-
Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4 - Q:-
Assign oxidation number to the underlined elements in each of the following species:
(a) NaH2PO4
(b) NaHSO4
(c) H4P2O7
(d) K2MnO4
(e) CaO2
(f) NaBH4
(g) H2S2O7
(h) KAl(SO4)2.12 H2O
- Q:-
What is the basic theme of organisation in the periodic table?
- Q:-
Explain the formation of a chemical bond.
- Q:-
Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only. - Q:-
A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?
Recently Viewed Questions of Class 11 Chemistry
- Q:-
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.
- Q:-
Predict the formula of the stable binary compounds that would be formed by the combination of the following pairs of elements. (a) Lithium and oxygen
(b) Magnesium and nitrogen
(c) Aluminium and iodine
(d) Silicon and oxygen
(e) Phosphorus and fluorine
(f) Element 71 and fluorine - Q:-
The enthalpy of combustion of methane, graphite and dihydrogen at 298 K are, –890.3 kJ mol–1 , –393.5 kJ mol–1, and –285.8 kJ mol–1 respectively. Enthalpy of formation of CH4(g) will be
(i) –74.8 kJ mol–1
(ii) –52.27 kJ mol–1
(iii) +74.8 kJ mol–1
(iv) +52.26 kJ mol–1
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The ionization constant of nitrous acid is 4.5 x 10-4. Calculate the pH of 0.04 M sodium nitrite solution and also its degree of hydrolysis.
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In Milikan’s experiment, static electric charge on the oil drops has been obtained by shining X-rays.
If the static electric charge on the oil drop is –1.282 × 10–18C, calculate the number of electrons present on it.
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Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume?
(a) PCl5 (g) ↔ PCl3 (g) + Cl2 (g)
(b) CaO (s) + CO2 (g) ↔ CaCO3 (s)
(c) 3Fe (s) + 4H2O (g) ↔ Fe3O4 (s) + 4H2 (g)
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For the following bond cleavages, use curved-arrows to show the electron flow and classify each as homolysis or heterolysis. Identify reactive intermediate produced as free radical, carbocation and carbanion.
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The value of Kc for the reaction
3O2 (g) ↔ 2O3 (g) is 2.0 ×10–50 at 25°C.
If the equilibrium concentration of O2 in air at 25°C is 1.6 ×10–2, what is the concentration of O3?
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