Equilibrium · Question 51

The dissociation constant of weak acid is 1 10-4. In order to prepare a buffer solution with a pH = 5, the [Salt]/[Acid] ratio should be

1. 4 : 5
2. 10 : 1
3. 5 : 4
4. 1 : 10

Given that the equilibrium constant for the reaction, 2SO2(g) + O2(g) 2SO3(g) has a value of 278 at a particular temperature. What is the value of the equilibrium constant for the following reaction at the same temperature ? SO3(g) SO2(g) + 12O2(g)

1. 1.8 10-3
2. 3.6 10-3
3. 6.0 10-2
4. 1.3 10-5

Given the reaction between 2 gases represented by A2 and B2 to give the compound AB(g), A2(g) + B2(g) 2AB(g) At equilibrium, the concentration of A2 = 3.0 10-3 M, of B2 = 4.2 10-3 M, of AB = 2.8 10-3 M If the reaction takes place in a sealed vessel at 527 , then the value of Kc will be

1. 2.0
2. 1.9
3. 0.62
4. 4.5

pH of a saturated solution of Ba(OH)2 is 12. The value of solubility product (Ksp) of Ba(OH)2 is

1. 3.3 10-7
2. 5.0 10-7
3. 4.0 10-6
4. 5.0 10-6

Equimolar solutions of the following substances were prepared separately. Which one of these will record the highest pH value ?

1. BaCl2
2. AlCl3
3. LiCl
4. BeCl2

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-