Equilibrium · Question 56

Buffer solutions have constant acidity and alkalinity because

1. these give unionised acid or base on reaction with added acid or alkali
2. acids and alkalies in these solutions are shielded from attack by other ions
3. they have large excess of H+ or OH- ions
4. they have fixed value of pH

In qualitative analysis, the metals of group I can be separated from other ions by precipitating them as chloride salts. A solution initially contains Ag+ and Pb2+ at a concentration of 0.10 M. Aqueous HCl is added to this solution until the Cl- concentration is 0.10 M. What will the concentrations of Ag+ and Pb2+ be at equilibrium ? ( Ksp for AgCl = 1.8 10-10, Ksp for PbCl2 = 1.7 10-5)

1. [Ag+] = 1.8 10-7 M, [ Pb2+] = 1.7 10-6 M
2. [Ag+] = 1.8 10-11 M, [ Pb2+] = 8.5 10-5 M
3. [Ag+] = 1.8 10-9 M, [ Pb2+] = 1.7 10-3 M
4. [Ag+] = 1.8 10-11 M, [ Pb2+] = 1.7 10-4 M

The value of H for the reaction X2(g) + 4Y2(g) 2XY4(g) is less than zero. Formation of XY4(g) will be favoured at

1. high temperature and high pressure
2. low pressure and low temperature
3. high temperature and low pressure
4. high pressure and low temperature

A buffer solution is prepared in which the concentration of NH3 is 0.30 M and the concentration of NH4+ is 0.20 M. If the equilibrium constant, Kb for NH3 equals 1.8 10-5, what is the pH of this solution? ( 2.7 = 0.43)

1. 9.08
2. 9.43
3. 11.72
4. 8.73

Which of the following is least likely to behave as Lewis base?

1. H2O
2. NH3
3. BF3
4. OH-

For the reaction, N2(g) + O2(g) 2NO(g), the equilibrium constant is K1. The equilibrium constant is K2 for the reaction, 2NO(g) + O2(g) 2NO2(g) What is K for the reaction, NO2(g) 12N2(g) + O2(g)

1. 12K1K2
2. 14K1K2
3. [ 1K1K2 ]1/2
4. 1K1K2

The reaction, 2A(g) + B(g) 3C(g) + D(g) is begun with the concentrations of A and B both at an initial value of 1.00 M. When equilibrium is reached, the concentration of D is measured and found to be 0.25 M. The value for the equilibrium constant for this reaction is given by the expression

1. [(0.75)3(0.25)] [(1.00)2(1.00)]
2. [(0.75)3(0.25)] [(0.50)2(0.75)]
3. [(0.75)3(0.25)] [(0.50)2(0.25)]
4. [(0.75)3(0.25)] [(0.75)2(0.25)]

If pH of a saturated solution of Ba(OH)2 is 12, the value of its Ksp is

1. 4.00 10-6 M3
2. 4.00 10-7 M3
3. 5.00 10-6 M3
4. 5.00 10-7 M3

What is [H+] in mol/L of a solution that is 0.20 M in CH3COONa and 0.10 M in CH3COOH? Ka for CH3COOH = 1.8 10-5

1. 3.5 10-4
2. 1.1 10-5
3. 1.8 10-5
4. 9.0 10-6

In which of the following equilibrium Kc and Kp are not equal?

1. 2NO(g) N2(g) + O2(g)
2. SO2(g) + NO2(g) SO3(g) + NO(g)
3. H2(g) + I2(g) 2HI(g)
4. 2C(s) + O2(g) 2CO(g)