Class 11 Chemistry - Chapter Equilibrium NCERT Solutions | Explain why pure liquids and solids can

Assuming complete dissociation, calculate the pH of the following solutions:

(a) 0.003 M HCl

(b) 0.005 M NaOH

(c) 0.002 M HBr

(d) 0.002 M KOH

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?

The pH of a sample of vinegar is 3.76. Calculate the concentration of hydrogen ion in it.

The ionization constant of acetic acid is 1.74 x 10^-5. Calculate the degree of dissociation of acetic acid in its 0.05 M solution. Calculate the concentration of acetate ion in the solution and its pH.

Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction:

CH₄ (g) + H₂O (g) ↔ CO (g) + 3H₂ (g)

(a) Write as expression for Kp for the above reaction.

(b) How will the values of Kp and composition of equilibrium mixture be affected by

  (i) increasing the pressure

  (ii) increasing the temperature

  (iii) using a catalyst ?

At 700 K, equilibrium constant for the reaction:

H2 (g) + I2 (g) ↔ 2HI (g)

is 54.8. If 0.5 mol L^–1 of HI(g) is present at equilibrium at 700 K, what are the concentration of H₂(g) and I₂(g) assuming that we initially started with HI(g) and allowed it to reach equilibrium at 700K?

At 473 K, equilibrium constant K_c for decomposition of phosphorus pentachloride, PCl₅ is 8.3 ×10^-3. If decomposition is depicted as,

PCl₅ (g) ↔  PCl₃ (g) + Cl₂ (g)          Δ_rH⁰ = 124.0 kJ mol^–1

(a) write an expression for Kc for the reaction.

(b) what is the value of Kc for the reverse reaction at the same temperature ?

(c) what would be the effect on K_c if (i) more PCl5 is added (ii) pressure is increased (iii) the temperature is increased ?

Find out the value of K_c for each of the following equilibria from the value of K_p:

(i) 2NOCl (g)  ↔  2NO (g) + Cl₂ (g);                   Kp  =  1.8 × 10^–2 at 500 K

(ii) CaCO₃ (s)  ↔  CaO(s) + CO₂(g);                  Kp  = 167 at 1073 K

Ionic product of water at 310 K is 2.7 x 10^-14. What is the pH of neutral water at this temperature?

Reaction between N₂ and O_2– takes place as follows:

2N₂ (g)  +  O₂ (g) ↔  2N₂O (g)

If a mixture of 0.482 mol N₂ and 0.933 mol of O₂ is placed in a 10 L reaction vessel and allowed to form N₂O at a temperature for which K_c = 2.0 × 10^–37, determine the composition of equilibrium mixture.

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.

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

Saline hydrides are known to react with water violently producing fire. Can CO₂, a well known fire extinguisher, be used in this case? Explain.

Arrange the following type of radiations in increasing order of frequency:

(a) radiation from microwave oven

(b) amber light from traffic signal

(c) radiation from FM radio

(d) cosmic rays from outer space and

(e) X-rays.

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.

The longest wavelength doublet absorption transition is observed at 589 and 589.6 nm. Calculate the frequency of each transition and energy difference between two excited states.

Explain, giving reasons, which of the following sets of quantum numbers are not possible.

a n = 0 l = 0 ml = 0  

b n = 1 l = 0 ml = 0  

c n = 1 l = 1 ml = 0   

d n = 2 l = 1 ml = 0  

e n = 3 l = 3 ml = – 3

f n = 3 l = 1 ml = 0 

Propanal and pentan-3-one are the ozonolysis products of an alkene? What is the structural formula of the alkene?

Explain why the following systems are not aromatic?

The quantum numbers of six electrons are given below. Arrange them in order of increasing energies. If any of these combination(s) has/have the same energy lists:

1. n = 4, l = 2, ml = –2 , ms = –1/2

2. n = 3, l = 2, ml= 1 , ms = +1/2

3. n = 4, l = 1, ml = 0 , ms = +1/2

4. n = 3, l = 2, ml = –2 , ms = –1/2

5. n = 3, l = 1, ml = –1 , ms= +1/2

6. n = 4, l = 1, ml = 0 , ms = +1/2

Energy of an electron in the ground state of the hydrogen atom is –2.18 × 10^–18 J. Calculate the ionization enthalpy of atomic hydrogen in terms of J mol^–1.

Discuss the principle of estimation of halogens, sulphur and phosphorus present in an organic compound.