NCERT Solutions class-11 Chemistry Hydrogen Part-2

17. Compare the structures of .

18. What do you understand by the term ‘auto-protolysis’ of water? What is its significance?

19. Consider the reaction of water with and suggest, in terms of oxidation and reduction, which species are oxidized/reduced.

20. Complete the following chemical reactions.

(i)

(ii)

(iii)

(iv)

(v)

Classify the above into (a) hydrolysis, (b) redox and (c) hydration reactions.

21. Describe the structure of the common form of ice.

Ans. Ice is the crystalline form of water. It takes a hexagonal form if crystallized at atmospheric pressure, but condenses to cubic form if the temperature is very low.

The three-dimensional structure of ice is represented as:

The structure is highly ordered and has hydrogen bonding. Each oxygen atom is surrounded tetrahedrally by four other oxygen atoms at a distance of 276 pm. The structure also contains wide holes that can hold molecules of appropriate sizes interstitially.

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22. What causes the temporary and permanent hardness of water?

23. Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.

24. Write chemical reactions to show the amphoteric nature of water.

1) Reaction with

2) Reaction with

3) Self-ionization of water

25. Write chemical reactions to justify that hydrogen peroxide can function as an oxidizing as well as reducing agent.

26. What is meant by ‘demineralised’ water and how can it be obtained?

27. Is demineralised or distilled water useful for drinking purposes? If not, how can it be made useful?

28. Describe the usefulness of water in biosphere and biological systems.

29. What properties of water make it useful as a solvent? What types of compound can it (i) dissolve, and (ii) hydrolyse?

30. Knowing the properties of , do you think that can be used for drinking purposes?

31. What is the difference between the terms ‘hydrolysis’ and ‘hydration’?

32. How can saline hydrides remove traces of water from organic compounds?

33. What do you expect the nature of hydrides is, if formed by elements of atomic numbers 15, 19, 23 and 44 with dihydrogen? Compare their behaviour towards water.

34. Do you expect different products in solution when aluminium (III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified water, and (iii) alkaline water? Write equations wherever necessary.

35. How does behave as a bleaching agent?

36. What do you understand by the terms:

(i) hydrogen economy

(ii) hydrogenation

(iii) ‘syngas’

(iv) water-gas shift reaction

(v) fuel-cell?