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.
Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.
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.
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?
Pay load is defined as the difference between the mass of displaced air and the mass of the balloon. Calculate the pay load when a balloon of radius 10 m, mass 100 kg is filled with helium at 1.66 bar at 27°C. (Density of air = 1.2 kg m–3 and R = 0.083 bar dm3 K–1 mol–1).
What are the major causes of water pollution? Explain.
Write Lewis dot symbols for atoms of the following elements: Mg, Na, B, O, N, Br.
Calculate the oxidation number of sulphur, chromium and nitrogen in H2SO5, Cr2O2- 7 and NO– 3. Suggest structure of these compounds. Count for the fallacy.
Assign the position of the element having outer electronic configuration
(i) ns2 np4 for n = 3 (ii) (n - 1)d2 ns2 for n = 4, and (iii) (n - 2) f7 (n - 1)d1 ns2 for n = 6, in the periodic table.
What will be the mass of one 12C atom in g?
What do you mean by green chemistry? How will it help decrease environmental pollution?
Bromine monochloride, BrCl decomposes into bromine and chlorine and reaches the equilibrium:
2BrCl (g) ↔ Br2 (g) + Cl2 (g) for which Kc= 32 at 500 K.
If initially pure BrCl is present at a concentration of 3.3 × 10–3 mol L–1, what is its molar concentration in the mixture at equilibrium?
One of the reaction that takes place in producing steel from iron ore is the reduction of iron(II) oxide by carbon monoxide to give iron metal and CO2.
FeO (s) + CO (g) ↔ Fe (s) + CO2 (g); Kp = 0.265 atm at 1050K
What are the equilibrium partial pressures of CO and CO2 at 1050 K if the initial partial pressures are: pCO= 1.4 atm and Pco2 = 0.80 atm
(i) The energy associated with the first orbit in the hydrogen atom is –2.18 × 10–18 J atom–1. What is the energy associated with the fifth orbit?
(ii) Calculate the radius of Bohr’s fifth orbit for hydrogen atom.
True right answer