Practice Questions on Solubility Equilibria of Sparingly Soluble Salts | Physical Chemistry PDF Download

Q.1. Common Ion effect can be used in which of the following cases?
(a) cloth making
(b) alcohol purification
(c) quantitative analysis
(d) qualitative analysis

Correct Answer is Option (c)
Common Ion effect is used in the purification of common salt, salting out of soap and qualitative analysis. In qualitative analysis, Ammonium Hydroxide is added in the presence of Ammonium Chloride to avoid the precipitation of V group radicals.

Q.2. For the dissociation of an electrolyte AxBy, Ksp is given as [Ay+]x[Bx+]y. What is Ksp?
(a) solubility product
(b) soluble product
(c) solution product
(d) solvent product

Correct Answer is Option (c)
Solubility product Ksp is defined as the product of the concentrations of the ions of the salt in its standard solution at a given temperature raised to the power of the ions produced by the dissociation of 1 mole of the salt.

Q.3. Solubility product can be used in predicting the solubility of a sparingly soluble salt.
(a) true
(b) false

Correct Answer is Option (a)
Yes, we can predict the solubility of a sparingly soluble salt, for example, consider the reaction; A_xB_y = xA^y+ + yB^x+, the solubility of a sparingly soluble salt is given by x^x.y^y.s^x+y, knowing the values of K_sp, x and y, the solubility of the salt can be calculated.

Q.4. If K_sp of a salt A₂B₃ is given by 1 x 10^-25. Then find the solubility of the salt?
(a) 10^-3
(b) 10^-4
(c) 10^-5
(d) 10^-8

Correct Answer is Option (c)
For the salt A_xB_y, (A_xB_y = xA^y+ + yB^x+), the solubility of a sparingly soluble salt is given by x^x.y^y.s^x+y. K_sp = x^x.y^y.s^x+y, where x = 2 and y = 3; K_sp = 108S5 = 1 x 10^-25. S = 10^-5. The solubility of the salt is given by 10^-5.

Q.5. Both the solubility product and ionic product are applicable to all types of solutions.
(a) true
(b) false

Correct Answer is Option (b)
Solubility of the product is only applicable to the saturated solutions, whereas an ionic product is applicable to all types of solutions. It is because the formation of a precipitate is dependent on the solubility product.

Q.6. The degree of dissociation of Ammonium hydroxide increases in the presence of Ammonium Chloride because of ____________.
(a) solubility product
(b) common Ion effect
(c) hydrolysis of the salt
(d) mixed salts

Correct Answer is Option (c)
Common Ion effect is defined as the separation of the dissociation of a weak electrolyte by the addition of a strong electrolyte having some common ion. Therefore the degree of dissociation of Ammonium hydroxide decreases in the presence of Ammonium Chloride due to common Ion effect.

Q.7. Hydroxide Ion concentration in calcium hydroxide and barium Hydroxide is an example of __________ solution.
(a) isochoric solution
(b) isohydric solutions
(c) hypo solution
(d) hyper solution

Correct Answer is Option (b)
In the solution of two electrolytes, if the common ions’ concentration (Hydroxide Ion concentration in calcium hydroxide and barium hydroxide solution) is equal, then on mixing there is zero change in the degree of association in both of the electrolytes, such solutions are called isohydric solutions.

Q.8. Precipitate is formed if ionic product is ______________
(a) greater than the solubility product
(b) less than the solubility product
(c) equal to the solubility product
(d) independent of the solubility product

Correct Answer is Option (a)
The concept of solubility product helps in predicting the formation of the precipitate. In general, if the ionic product is greater than the solubility product, the precipitate is formed and if the ionic product is less than the solubility product, the precipitate is not formed.

Q.9. A salt is soluble is the solubility is ________.
(a) less than 0.01 M
(b) in between 0.01 M and 0.1 M
(c) greater than 0.01 M
(d) greater than 0.1 M

Correct Answer is Option (d)
A salt is soluble if the solubility is greater than 0.1 M. A salt is slightly soluble if the solubility is between 0.01 M and 0.1 M and the salt is sparingly soluble if the solubility is less than 0.01 M.

Q.10. The solubility for the salts of the type AB₃ is given by ___________.
(a) (K_sp 27)1/4
(b) (K_sp/27)1/5
(c) (K_sp/27)3/4
(d) (K_sp/27)1/4

Correct Answer is Option (d)

Clarification: For the salt A_xB_y, (A_xB_y = xA^y+ + yB^x+), the solubility of a sparingly soluble salt is given by x^x.y^y.s^x+y. K_sp = x^x.y^y.s^x+y, where x = 1 and y = 3; K_sp = 27S⁴, by rearranging, we get solubility denoted by S as (K_sp/27)^1/4.