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All questions of Ionic Equilibrium for Chemistry Exam

The [Ag+(aq)] = 10-5 in a solution .The [Cl(aq)] to precipitate AgCl having Ksp of 1.8×10-10 M2 is — M
  • a)
    10-7
  • b)
    10-8
  • c)
    10-9
  • d)
    10-5
Correct answer is option 'D'. Can you explain this answer?

Hansa Sharma answered
For precipitation, Qrkn > Ksp, then tto establish equilibrium, ions will combine to give molecule as ppt.
So applying the above concept,
 1.8×10-10 < [Ag+][Cl-]
 1.8×10-10 < 10-5 × [Cl-]
Or [Cl-] > 1.8×10-5
By seeing the option, only option d satisfies this condtion.

Solubility of BaCl2 if Ksp is 10-6 at 25°C is
  • a)
    Cannot be predicted
  • b)
    6.3 10-3 M
  • c)
    10-6 M
  • d)
    10-3 M
Correct answer is option 'B'. Can you explain this answer?

Suresh Reddy answered
The correct answer is Option B.
BaCl₂ ⇔ Ba²⁺ + 2Cl⁻
Ksp = (s)(2s)² = 4s³
Given, 4s³ = 10⁻⁶
⇒s³ = 0.25 ⨯ 10⁻⁶
⇒s = (0.25)³ ⨯ 10⁻²
⇒s = 0.629 ⨯ 10⁻²
⇒s = 6.3 ⨯ 10⁻³

The solubility product expression for silver(I) sulphide, using x to represent the molar concentration of silver(I) and y to represent the molar concentration of sulphide, is formulated as:
  • a)
    x2y2
  • b)
    xy3
  • c)
    x2y
  • d)
    xy2
Correct answer is option 'C'. Can you explain this answer?

Om Desai answered
The correct answer is Option C.
The ionization equilibrium of silver (I) sulfide is 
Ag2S⇌2Ag+ +S2
The solubility product expression for silver (I) sulfide is KSP[Ag+]2 [S2].
But [Ag+]2 = x and [S2−] = y.
Hence the expression for the solubility product becomes KSP[Ag+]2 [S2−] = x2y.

 What is the Ksp expression for the salt PbI2?
  • a)
    [Pb2+][2I]2  
  • b)
    [Pb2+][I2]2
  • c)
    [Pb2+][2I]
  • d)
    [Pb2+][I]2
Correct answer is option 'D'. Can you explain this answer?

Jyoti Dey answered
A general equation of equilibrium constant for a reaction of dissociation of PbI2 as PbI2⇌Pb2++2I-can be written as,

But we know that Ksp is the equilibrium constant at the saturated level. At saturation, no more PbIwill dissolve. Thus the concentration of PbI2 will be constant and can be taken as 1.
Therefore the above equation can be written as,

Precipitation requires
  • a)
    Ionic product to be less than solubility product
  • b)
    Ionic product to be equal to solubility product
  • c)
    Ionic product to be more than pH
  • d)
    Ionic product to be more than solubility product
Correct answer is option 'D'. Can you explain this answer?

Ananya Datta answered
The correct answer is option 'D': Ionic product to be more than solubility product.

Explanation:

1. Understanding Solubility and Ionic Product:

Solubility refers to the maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature. It is usually expressed in terms of grams of solute per 100 grams of solvent.

Ionic product (Q) is the product of the concentrations (or activities) of ions in a solution, raised to the power of their stoichiometric coefficients in the balanced chemical equation.

2. Relationship between Ionic Product and Solubility Product:

The solubility product (Ksp) is a constant value that represents the equilibrium between a solid solute and its ions in a solution. It is the product of the concentrations (or activities) of the ions, each raised to the power of their stoichiometric coefficients.

Ionic product (Q) is a measure of the actual concentrations (or activities) of ions in a solution, regardless of whether the solution is at equilibrium or not. If Q is less than Ksp, the solution is unsaturated and more solute can dissolve. If Q is equal to Ksp, the solution is at equilibrium and the solution is saturated. If Q is greater than Ksp, the solution is supersaturated and precipitation will occur.

3. Precipitation and the Ionic Product:

When the ionic product (Q) exceeds the solubility product (Ksp), the solution becomes supersaturated with respect to the solute. This means that there are more ions in the solution than can be maintained in equilibrium with the solid solute.

As a result, the excess ions will start to come together and form a solid precipitate. This precipitation process is driven by the need to reduce the concentration of ions in the solution and restore equilibrium according to Le Chatelier's principle. The precipitate will continue to form until the ionic product (Q) equals the solubility product (Ksp) and the solution becomes saturated again.

Therefore, precipitation occurs when the ionic product (Q) is greater than the solubility product (Ksp). This is why the correct answer is option 'D': Ionic product to be more than solubility product.

Summary:

- Precipitation occurs when the ionic product (Q) exceeds the solubility product (Ksp).
- The ionic product is a measure of the actual concentrations (or activities) of ions in a solution.
- The solubility product is a constant value representing the equilibrium between a solid solute and its ions in a solution.
- When the solution becomes supersaturated, precipitation will occur to restore equilibrium.

Solubility of a soluble salt is
  • a)
    more than 0.1M
  • b)
    less than 0.01M
  • c)
    more than 0.001M
  • d)
    more than 0.01M
Correct answer is option 'A'. Can you explain this answer?

Shreya Gupta answered
A salt is soluble if it dissolves in water to give a solution with a concentration of at least 0.1 moles per liter at room temperature.

 Solubility product is defined as
  • a)
    product of molar concentration of ions of a salt as per stoichiometry in a supersaturated solution
  • b)
    product of molar concentration of ions of a salt as per stoichiometry in a saturated solution at STP
  • c)
    product of molar concentration of ions of a salt as per stoichiometry in a saturated solution
  • d)
    product of molar concentration of ions of a salt as per stoichiometry in an unsaturated solution
Correct answer is option 'C'. Can you explain this answer?

Jyoti Kumar answered
Understanding Solubility Product
The solubility product (Ksp) is a crucial concept in chemistry, particularly in the context of ionic compounds and their solubility in water.
Definition of Solubility Product
- The solubility product is defined as the product of the molar concentrations of the ions of a salt, each raised to the power of their respective coefficients in the balanced chemical equation.
Why Option C is Correct
- The correct answer is option 'C' because the solubility product is specifically applicable to a saturated solution.
- In a saturated solution, the maximum amount of solute has dissolved, and the system is at equilibrium.
Key Features of Saturated Solutions
- Equilibrium State: In a saturated solution, the rates of dissolution and precipitation of the solute are equal, ensuring that the concentrations of the dissolved ions remain constant.
- Stoichiometry: The concentrations of the ions are determined by the stoichiometry of the dissolution reaction, which is crucial for calculating Ksp.
- Temperature Dependency: The solubility product is also temperature-dependent, meaning that changes in temperature can affect the solubility of the salt and, consequently, its Ksp value.
Importance of Ksp
- The Ksp value helps in predicting whether a precipitate will form when solutions are mixed.
- It is essential for understanding various chemical processes, including those in biological systems, environmental chemistry, and industrial applications.
In conclusion, the solubility product is a vital concept that specifically pertains to saturated solutions, making option 'C' the correct choice.

 The molar solubility of PbBr2 is 2.17 x 10-3 M at a certain temperature. Calculate Kspfor PbBr2
  • a)
    4.1 x 10-8
  • b)
    6.2 x 10-6
  • c)
    6.4 x 10-7
  • d)
    3.4 x 106
Correct answer is option 'A'. Can you explain this answer?

Upasana Bose answered
Molar solubility(s) for PbBr2 =  2.17×10-3 M
PbBr2   ⇌   Pb+2 + 2Br-
s                     
s          2s
Ksp = [Pb+2][Br-]2
= [s][s]2
= 4s3  =  4(2.17×10-3)3
= 4.1×10-8

When in a saturated solution of NaCl, HCl is passed, pure precipitate of NaCl is formed. This is due to the fact:
  • a)
    That solubility of NaCl decreases
  • b)
    That HCl is strong acid
  • c)
    That the ionic product of NaCl exceeds the solubility product of NaCl.
  • d)
    That HCl is highly soluble in water
Correct answer is option 'C'. Can you explain this answer?

Nandini Iyer answered
In saturated solution of NaCl,equillibrium is established between ions and unionised NaCl. When HCl gas is passed through saturated solution of NaCl,it is completely dissociated to form H+ and Cl- ions. Cl- ion is common to both electrolyte ,hence Cl- ion concentration in solution increases.

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