20 Questions
What is the unit of Ksp?
Mol^2/L^2
What is the molarity of oxalic acid solution used in the experiment?
0.1 M
What is the purpose of adding 2N H2SO4 in the experiment?
To decrease the pH of the solution
What is the mole ratio of oxalic acid to potassium permanganate?
2:1
What is the unit of solubility?
mg/L
What is the purpose of heating the solution to 60-70°C in the experiment?
To increase the rate of reaction
What is the concentration of potassium permanganate used in the experiment?
Not specified
What is the purpose of repeating the titration three times?
To increase the accuracy of the result
Why is nitric acid not used in the standardization of potassium permanganate?
Because it oxidizes potassium permanganate
What is the mole ratio of iron to potassium permanganate?
1:5
What is the difference between a solution, suspension, and precipitate?
Solution is a homogeneous mixture, suspension is a heterogeneous mixture, and precipitate is a solid formed from a solution.
What is the solubility product constant (Ksp) of a salt?
The product of the concentration of the ions that are present in a saturated solution of the salt.
What does the Ksp value of a substance represent?
The level at which a solute dissolves in a solution.
What is the Ksp value of CuBr if its molar solubility is 2.20x10-4 mol/L at 25°C?
4.0x10-8 mol2/L2
What is the Ksp value of Bi2S3?
1.1x10-73 mol/L3
Will NiCO3 precipitate in a solution that is 1.5 x 10–6 M in Ni2+ and 6.0 x 10–4 M in CO32–?
No, because Q < Ksp.
Which forms first, solid AgI or solid AgCl?
AgI forms first.
What is the formula for the Ksp of Pb3(PO4)2?
[Pb2+]3.[PO43-]2
What is the reaction quotient Q?
The product of the concentration of the ions that are present in a solution.
What happens when the reaction quotient Q is less than the Ksp value?
No precipitate forms.
Study Notes
Precipitation Titration
- A solution is a homogeneous mixture of two or more substances, whereas a suspension is a heterogeneous mixture, and a precipitate is an insoluble solid that forms in a solution.
Solubility Product Constant (Ksp)
- The solubility product constant (Ksp) is the product of the concentration of the ions that are present in a saturated solution of an ionic compound.
- Ksp represents the level at which a solute dissolves in a solution; the more soluble a substance is, the higher the Ksp value it has.
- For a salt AaBb, Ksp = [A+]a.[B-]b.
Examples of Ksp Calculations
- For AgCl, Ksp = [Ag+].[Cl-].
- For Pb3(PO4)2, Ksp = [Pb2+]3.[PO43-]2.
Calculating Ksp Values
- Copper(I) bromide has a measured molar solubility of 2.20x10-4 mol/L at 25°C, so Ksp = 4.0x10-8 mol2/L2.
- Bismuth sulfide (Bi2S3) has a solubility of 1.0x10-15 mol/L at 25°C, so Ksp = 1.1 x 10-73.
Precipitation Reaction
- A solution is 1.5 x 10–6 M in Ni2+, and Na2CO3 is added to make the solution 6.0 x 10–4 M in CO32–. Since Q < Ksp, no precipitate will be formed.
Titration
Standardization of Potassium Permanganate
- Transfer 10 ml oxalic acid solution (0.1 M) into a conical flask and add 20 ml, 2N H2SO4.
- Heat the solution to 60-70°C and titrate slowly with potassium permanganate to the faint pink colour end-point.
Redox Titration
- Standardization of potassium permanganate is used for the determination of iron.
- Transfer 10 ml iron solution into a conical flask and add 20 ml, 2N H2SO4.
- Titrate slowly with potassium permanganate to the faint pink colour end-point.
Learn about the difference between solution, suspension, and precipitate, and understand the concept of solubility product constant (Ksp) in chemistry.
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