NIOS Class 12 Chemistry Chapter 11 Chemical Equilibrium Solutions English Medium As Per New Syllabus to each chapter is provided in the list so that you can easily browse throughout different chapters NIOS Class 12 Chemistry Chapter 11 Chemical Equilibrium Notes in English and select need one. NIOS Class 12 Chemistry Solutions English Medium Download PDF. NIOS Study Material of Class 12 Chemistry Notes Paper Code: 313.
NIOS Class 12 Chemistry Chapter 11 Chemical Equilibrium
Also, you can read the NIOS book online in these sections Solutions by Expert Teachers as per National Institute of Open Schooling (NIOS) Book guidelines. These solutions are part of NIOS All Subject Solutions. Here we have given NIOS Class 12 Chemistry Notes, NIOS Senior Secondary Course Chemistry Solutions in English for All Chapter, You can practice these here.
Chemical Equilibrium
Chapter: 11
| Module – V: Chemical Dynamics |
INTEXT QUESTIONS 11.1
1. What is a reversible reaction? Give two examples.
Ans: A chemical reaction is said to be reversible, if under certain conditions its products also react and form back the reactants.
Examples :
H₂ (g) + I₂ (g) ⇌ 2HI (g)
2SO₂ (g) + O₂ (g) ⇌ 2SO₃ (g).
2. When does a reaction reach equilibrium state?
Ans: A reaction reaches an equilibrium state when two opposing reactions occur
at the same rate and balance each other at a particular temperature.
3. How would you know whether a system has reached the equilibrium state or not?
Ans: When a system reaches the equilibrium state, its temperature, pressure and concentrations of all the reactants and products do not change any further with time.
4. Give two examples of physical equilibrium.
Ans: (i) Water-vapour system in a closed container at a constant temperature.
(ii) A saturated solution containing some undissolved solute at a constant temperature.
5. Give two example each of chemical homogeneous and heterogeneous equilibria.
Ans: (i) Homogeneous systems:
H₂ (g) + I₂ (g) ⇌ 2HI (g)
2SO₂ (g) + O₂(g)⇌ 2SO₃ (g)
(ii) Heterogeneous systems :
CaCO₃(s) ⇌ CaO (s) + CO₂(g)
Zn (s) + CuSO₄(aq) ⇌ Cu (s) + ZnSO₄(aq).
INTEXT QUESTIONS 11.2
1. For a reversible reaction:
2A + B ⇌ 3C + 3D
Write the expression for the equilibrium constant.
Ans: K = {[C]³ [D]³}\[A]² [B]
2. What is the relation between Kₚ and Kc.
Ans: Kp = Kc(RT)Δng
3. (i) Apply the law of equilibrium to the following and write the expression for Kₚ and Kc.
(a) CO₂(g) + H₂(g) ⇌ CO (g) + H₂O (g)
(b) I₂ (s) ⇌ I₂ (g)
(ii) For the above reaction write equation for Kp and Kc.
Ans: (i) (a) Kc= {[CO][H₂O]}\[CO₂ ][H₂]
Kp = {p(CO) × p(H₂O)}/{p(CO₂) × p(H₂)}
(b) Kc= [I2]; Kp = PI2
(ii) For the first reaction Δng
= (1 + 1) – (1 – 1) = 0, hence Kc = Kp
while for the second reaction Δng = 1 – 0 = + 1
∴ Kp = Kc (RT) or Kc = KpRT or Kc < Kp.
4. The equilibrium constant for the reactions:
(i) N₂ (g) + 3H₂(g) ⇌ 2NH₃ (g)
are K₁ and K₂ respectively. What is the relation between them.
Ans: K1= ([NH₃ ]²)/ ([N₂ ][H₂ ]³) and
K2 = ([NH₃ ]²/³)/([N₂ ]¹/³ [H₂ ])
∴ K1 = [K2]3.
5. What is the significance of the magnitude of equilibrium constant?
Ans: It is a measure of the extent up to which a reaction proceeds before the equilibrium is reached.
INTEXT QUESTIONS 11.3
1. What is Le Chatelier’s principle?
Ans: Le Chatelier’s principle states that when a system at equilibrium is disturbed by changing concentration, pressure or temperature, a ‘net’ change occurs in a direction that tends to neutralize the effect of the disturbing factor.
2. What are the factors that can affect a system at equilibrium?
Ans: Changes in pressure, temperature and concentrations of reactants or products.
3. What will happen to solid-vapour equilibrium when the temperature and pressure are decreased.
Ans: When the temperature is decreased some vapour will condense and when the pressure is decreased some solid will sublime.
4. (a) Which of the following will result in ‘net’ forward reaction in case of:
A (g) + 2B (g) U C (s) + D (g) ; ΔH = + ve
(i) addition of C.
(ii) addition of A.
(iii) decrease in pressure.
(iv) increase in temperature.
Ans: (a) (ii) and (iv).
(b) What are the most favourable conditions for the formation of C and D?
Ans: High temperature, increase in pressure, presence of a catalyst and continuous removal of D.
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