Equilibrium · Question 24

Dissociation of a gas A2 takes place according to the following chemical reaction. At equilibrium, the total pressure is 1 bar at 300 K. A2(g) 2A(g) The standard Gibbs energy of formation of the involved substances has been provided below: arraycc Substance & Gf /kJ mol-1 \ A2 & -100.00 \ A & -50.832 array The degree of dissociation of A2(g) is given by (x 10-2)1/2 where x = . (Nearest integer). [ Given : R = 8 J mol-1 K-1, 2 = 0.3010, 3 = 0.48 ] Assume degree of dissociation is not negligible.

Which of the following mixture gives a buffer solution with pH = 9.25 ? Given : pKb (NH4OH) = 4.75

1. 0.5 M NH4OH (0.2 L) + 0.2 M HCl (0.5 L)
2. 0.2 M NH4OH (0.5 L) + 0.1 M HCl (0.5 L)
3. 0.2 M NH4OH (0.4 L) + 0.1 M HCl (1 L)
4. 0.4 M NH4OH (1 L) + 0.1 M HCl (1 L)

For the reaction, N2O4 2NO2, graph is plotted as shown below. Identify correct statements. [figure] Choose the correct answer from the options given below :

1. C and E only
2. D and E only
3. A and D only
4. B and C only

The first and second ionization constants of H2X are 2.5 10-8 and 1.0 10-13 respectively. The concentration of X2- in 0.1 M H2X solution is 10-15 M. (Nearest Integer)

The equilibrium constant for decomposition of H2O(g) H2O(g) H2(g) + 12O2(g); G = 92.34 kJ mol-1 is 8.0 10-3 at 2300 K and total pressure at equilibrium is 1 bar. Under this condition, the degree of dissociation ( ) of water is 10-2 (nearest integer value). [Assume is negligible with respect to 1]

An aqueous solution of HCl with pH 1.0 is diluted by adding equal volume of water (ignoring dissociation of water). The pH of HCl solution would (Given 2 = 0.30)

1. increase to 1.3
2. reduce to 0.5
3. increase to 2
4. remain same

One litre buffer solution was prepared by adding 0.10 mol each of NH3 and NH4Cl in deionised water. The change in pH on addition of 0.05 mol of HCl to the above solution is 10-2. (Nearest integer) Given : pKb of NH3 = 4.745 and 10 3 = 0.477

The pH of a 0.01 M weak acid HX (Ka = 4 10-10) is found to be 5. Now the acid solution is diluted with excess of water so that the pH of the solution changes to 6. The new concentration of the diluted weak acid is given as x 10-4 M. The value of x is (nearest integer)

x mg of Mg(OH)2 (molar mass = 58 g mol-1) is required to be dissolved in 1.0 L of water to produce a pH of 10.0 at 298 K. The value of x is mg. (Nearest integer) (Given : Mg(OH)2 is assumed to dissociate completely in H2O)

In the following system, PCl5(g) PCl3(g) + Cl2(g) at equilibrium, upon addition of xenon gas at constant T & p, the concentration of

1. PCl5, PCl3 & Cl2 remain constant
2. PCl3 will increase
3. Cl2 will decrease
4. PCl5 will increase