Write chemical reactions to show the amphoteric nature of water.
The amphoteric nature of water can be described on the basis of the following reactions:
1) Reaction with H2S
The reaction takes place as:
In the forward reaction, H2O(l) accepts a proton from H2S(aq). Hence, it acts as a Lewis base.
2) Reaction with NH3
The reaction takes place as:
In the forward reaction, H2O(l) denotes its proton NH3(aq). Hence, it acts as a Lewis acid.
3) Self-ionization of water
In the reaction, two water molecules react as:
Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.
Compare the structures of H2O and H2O2.
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.
Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.
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.
What is meant by 'demineralised' water and how can it be obtained?
What causes the temporary and permanent hardness of water?
How does H2O2 behave as a bleaching agent?
Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?
Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?
How do you account for the formation of ethane during chlorination of methane?
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
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
What are the common physical and chemical features of alkali metals?
Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4
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
What is the basic theme of organisation in the periodic table?
Explain the formation of a chemical bond.
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.
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?
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
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
Explain why is there a phenomenal decrease in ionisation enthalpy from carbon to silicon?
What would have happened if the greenhouse gases were totally missing in the earth's atmosphere? Discuss.
What do you mean by ozone hole? What are its consequences?
Explain the formation of H2 molecule on the basis of valence bond theory.
Write the atomic number of the element present in the third period and seventeenth group of the periodic table.
Which one of the following alkali metals gives hydrated salts?
(a) Li (b) Na (c) K (d) Cs
Which out of NH3 and NF3 has higher dipole moment and why?
What is meant by the term bond order? Calculate the bond order of: N2, O2,O2+,and O2-.
True right answer