Q.1.
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?
Q.2. What is Kc for the following equilibrium when the equilibrium concentration of each substance is:
[SO2] = 0.60 M, [O2] = 0.82 M and [SO3] = 1.90 M ?
2SO2(g) + O2(g) ⇌ 2SO3(g)
Q.3. At a certain temperature and total pressure of 105 Pa, iodine vapour contains 40% by volume of I atoms
I2(g) ⇌ 2I (g)
Calculate Kp for the equilibrium.
Q.4. Write the expression for the equilibrium constant, Kc for each of the following reactions:
(i) 2NOCl(g) ⇌ 2NO(g) + Cl2(g)
(ii) 2Cu(NO3)2(s) ⇌ 2CuO(s) + 4NO2(g) + O2(g)
(iii) CH3COOC2H5(aq) + H2O(l) ⇌ CH3COOH(aq) + C2H5 OH (aq)
(iv) Fe3+(aq) + 3OH– (aq) ⇌ Fe(OH)3(s)
(v) I2(s) + 5F2 ⇌ 2IF5
Q.5. Find out the value of Kc for each of the following equilibria:
(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
Q.6. For the following equilibrium, Kc = 6.3 × 1014 at 1000 K
NO (g) + O3(g) ⇌ NO2(g) + O2(g)
Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is Kc, for the reverse reaction?
Q.7. Explain why pure liquids and solids can be ignored while writing the equilibrium constant expression?
Q.8. Reaction between N2 and O2 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 Kc = 2.0 × 10–37, determine the composition of equilibrium mixture.
Q.9. Nitric oxide reacts with Br2 and gives nitrosyl bromide as per reaction given below:
2NO(g) + Br2(g) ⇌ 2NOBr (g)
When 0.087 mol of NO and 0.0437 mol of Br2 are mixed in a closed container at constant temperature, 0.0518 mol of NOBr is obtained at equilibrium. Calculate equilibrium amount of NO and Br2.
Q.10. At 450K, Kp = 2.0 × 1010 /bar for the given reaction at equilibrium.
2SO2(g) + O2(g) ⇌ 2SO3(g)
What is Kc at this temperature ?
Q.11. A sample of HI(g) is placed in flask at a pressure of 0.2 atm. At equilibrium the partial pressure of HI(g) is 0.04 atm. What is Kp for the given equilibrium ?
2HI(g) ⇌ H 2(g) + I2(g)
Q.12. A mixture of 1.57 mol of N2, 1.92 mol of H2 and 8.13 mol of NH3 is introduced into a 20 L reaction vessel at 500 K. At this temperature, the equilibrium constant, Kc for the reaction N2(g) + 3H2(g) ⇌ 2NH3(g) is 1.7 × 102. Is the reaction mixture at equilibrium? If not, what is the direction of the net reaction?
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