Equilibrium · Question 10

The pH of a solution obtained by mixing 5 mL of 0.1 M NH4OH solution with 250 mL of 0.1 M NH4Cl solution is 10-2. (Nearest integer) Given: pKb(NH4OH) = 4.74 2 = 0.30 3 = 0.48 5 = 0.70

20 mL of a solution of acetic acid required 28.4 mL of 0.1 M NaOH for its neutralization. A solution (X) was prepared by mixing 20 mL of the above acetic acid and 14.2 mL of 0.1 M NaOH solution. What is the pH of the solution (X)? (pKa value of acetic acid is 4.75).

1. 7.0
2. 4.75
3. 3.5
4. 4.82

For the following reaction at 50 °C and at 2 atm pressure, 2N2O5(g) 2N2O4(g) + O2(g) N2O5 is 50% dissociated. The magnitude of standard free energy change at this temperature is x. x = J mol-1 [Nearest integer]. Given : R = 8.314 J mol-1 K-1, log 2 = 0.30, log 3 = 0.48, ln 10 = 2.303, °C + 273 = K

The solubility product constants of Ag2CrO4 and AgBr are 32x and 4y respectively at 298 K. The value of ( molarity of Ag2CrO4molarity of AgBr ) can be expressed as :

1. 2 [3]xy
2. 2 xy
3. xy
4. [3]x y

The first and second ionization constants of a weak dibasic acid H2A are 8.1 10-8 and 1.0 10-13 respectively. 0.1 mol of H2A was dissolved in 1 L of 0.1 M HCl solution. The concentration of HA- in the resultant solution is:

1. 0.1 M
2. 9.53 10-6 M
3. 8.1 10-8 M
4. 1.0 10-13 M

At 25°C, 20.0 mL of 0.2 M weak monoprotic acid HX is titrated against 0.2 M NaOH. The pH of the solution (a) at the start of the titration (when NaOH has not been added) and (b) when 10 mL of NaOH is added respectively, are : Given : Ka = 5 10-4 pKa = 3.3 1

1. array|c|c| (a) & (b) \ 0.7 & 2.0 \ array
2. array|c|c| (a) & (b) \ 2.0 & 3.3 \ array
3. array|c|c| (a) & (b) \ 1.1 & 2.2 \ array
4. array|c|c| (a) & (b) \ 3.0 & 2.2 \ array

Consider a weak base 'B' of pKb = 5.699. 'x' mL of 0.02 M HCl and 'y' mL of 0.02 M weak base 'B' are mixed to make 100 mL of a buffer of pH 9 at 25 . The values of 'x' and 'y' respectively are : [Given : 2 = 0.3010, 3 = 0.4771, 5 = 0.699]

1. arraycc x & y \ 42.7 & 57.3 array
2. arraycc x & y \ 14.3 & 85.7 array
3. arraycc x & y \ 85.7 & 14.3 array
4. arraycc x & y \ 11.1 & 88.9 array

Consider the dissociation equilibrium of the following weak acid HA H+(aq) + A-(aq) If the pKa of the acid is 4, then the pH of 10 mM HA solution is . (Nearest integer) [Given: The degree of dissociation can be neglected with respect to unity]

Observe the following equilibrium in a 1 L flask. A(g) B(g) At T(K), the equilibrium concentrations of A and B are 0.5 M and 0.375 M respectively. 0.1 moles of A is added into the flask and heated to T(K) to establish the equilibrium again. The new equilibrium concentrations (in M) of A and B are respectively

1. 0.742, 0.557
2. 0.367, 0.275
3. 0.53, 0.4
4. 0.557, 0.418

Consider two Group IV metal ions X2+ and Y2+. A solution containing 0.01 M X2+ and 0.01 M Y2+ is saturated with H2S. The pH at which the metal sulphide YS will form as a precipitate is . (Nearest integer) (Given: Ksp(XS) = 1 10-22 at 25 , Ksp(YS) = 4 10-16 at 25 , [H2S] = 0.1 M in solution, Ka1 Ka2(H2S) = 1.0 10-21, 2 = 0.30, 3 = 0.48, 5 = 0.70)