Equilibrium

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

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below

1. Statement I is true but Statement II is false
2. Statement I is false but Statement II is true
3. Both Statement I and Statement II are true
4. Both Statement I and Statement II are false

If equal volumes of AB2 and XY (both are salts) aqueous solutions are mixed, which of the following combination will give a precipitate of AY2 at 300 K ? (Given Ksp (at 300 K) for AY2 = 5.2 10-7)

1. 2.0 10-4 M AB2, 0.8 10-3 M XY
2. 2.0 10-2 M AB2, 2.0 10-2 M XY
3. 1.5 10-4 M AB2, 1.5 10-3 M XY
4. 3.6 10-3 M AB2, 5.0 10-4 M XY

Consider the following equilibrium, CO(g) + 2H2(g) CH3OH(g) 0.1 mol of CO along with a catalyst is present in a 2 dm3 flask maintained at 500 K. Hydrogen is introduced into the flask until the pressure is 5 bar and 0.04 mol of CH3OH is formed. The Kp is 10-3 (nearest integer). Given : R = 0.08 dm3 bar K-1 mol-1 Assume only methanol is formed as the product and the system follows ideal gas behaviour.

Consider the following chemical equilibrium of the gas phase reaction at a constant temperature : A(g) B(g) + C(g) If p is the total pressure, Kp is the pressure equilibrium constant and is the degree of dissociation, then which of the following is true at equilibrium?

1. If Kp value is extremely high compared to p, becomes much less than unity
2. When p increases, increases
3. If p value is extremely high compared to Kp, 1
4. When p increases, decreases

At temperature T, compound AB2(g) dissociates as AB2(g) AB(g) + 12B2(g) having degree of dissociation x (small compared to unity). The correct expression for x in terms of Kp and p is:

1. Kp
2. [3] 2Kp2p
3. [3] 2Kpp
4. [4] 2Kpp

Consider the equilibrium CO(g) + 3H2(g) CH4(g) + H2O(g) If the pressure applied over the system increases by two fold at constant temperature then

1. (A) and (B) only
2. (A), (B) and (D) only
3. (B) and (C) only
4. (A), (B) and (C) only

A weak acid HA has degree of dissociation x. Which option gives the correct expression of (pH - pKa)?

1. ( 1-xx )
2. 0
3. (1+2x)
4. ( x1-x )

Ice and water are placed in a closed container at a pressure of 1 atm and temperature 273.15 K. If pressure of the system is increased 2 times, keeping temperature constant, then identify correct observation from following

1. Liquid phase disappears completely.
2. The amount of ice decreases.
3. The solid phase (ice) disappears completely.
4. Volume of system increases.

Arrange the following in increasing order of solubility product : Ca(OH)2, AgBr, PbS, HgS

1. PbS < HgS < Ca(OH)2 < AgBr
2. HgS < AgBr < PbS < Ca(OH)2
3. HgS < PbS < AgBr < Ca(OH)2
4. Ca(OH)2 < AgBr < HgS < PbS

Ksp for Cr(OH)3 is 1.6 10-30. What is the molar solubility of this salt in water?

1. [5]1.8 10-30
2. 1.8 10-3027
3. [4] 1.6 10-3027
4. [2]1.6 10-30

37.8 g N2O5 was taken in a 1 L reaction vessel and allowed to undergo the following reaction at 500 K 2N2O5(g) 2N2O4(g) + O2(g) The total pressure at equilibrium was found to be 18.65 bar. Then, Kp = 10-2 [nearest integer] Assume N2O5 to behave ideally under these conditions. Given: R = 0.082 bar L mol-1 K-1

For the reaction, H2(g)+I2(g) 2HI(g) Attainment of equilibrium is predicted correctly by :

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Which of the following happens when NH4OH is added gradually to the solution containing 1 M A2+ and 1M B3+ ions? Given : Ksp [A(OH)2] = 9 10-10 and Ksp [B(OH)3] = 27 10-18 at 298 K.

1. A(OH)2 will precipitate before B(OH)3
2. A(OH)2 and B(OH)3 will precipitate together
3. Both A(OH)2 and B(OH)3 do not show precipitation with NH4OH
4. B(OH)3 will precipitate before A(OH)2

If 1 mM solution of ethylamine produces pH=9, then the ionization constant (Kb) of ethylamine is 10-x. The value of x is (nearest integer). [The degree of ionization of ethylamine can be neglected with respect to unity.]

pH of water is 7 at 25 C. If water is heated to 80 C, it's pH will :

1. Decrease
2. Remains the same
3. Increase
4. H+ concentration increases, OH- concentration decreases

Consider the reaction X2Y(g) X2(g) + 12Y2(g) The equation representing correct relationship between the degree of dissociation (x) of X2Y(g) with its equilibrium constant Kp is . Assume x to be very very small.

1. x = [3] KpP
2. x = [3] Kp2P
3. x = [3] 2 Kp2P
4. x = [3] 2KpP

A vessel at 1000 K contains CO2 with a pressure of 0.5 atm. Some of CO2 is converted into CO on addition of graphite. If total pressure at equilibrium is 0.8 atm, then Kp is :

1. 0.18 atm
2. 0.3 atm
3. 3 atm
4. 1.8 atm

The molar solubility(s) of zirconium phosphate with molecular formula ( Zr4+ )3 ( PO43- )4 is given by relation :

1. ( Ksp5348 )1/6
2. ( Ksp8435 )1/7
3. ( Ksp6912 )1/7
4. ( Ksp9612 )1/3