KELARUTAN DAN HASIL KALI KELARUTAN (Ksp) : KIMIA SMA KELAS 11

Summary

This educational video focuses on the solubility of salts, explaining the concept through various examples. It begins with the dissolution of NaCl in water, covering unsaturated and saturated solutions. The script details the concept of solubility (the maximum amount of solute that can dissolve in a solvent at a given temperature) and introduces the solubility product constant (Ksp), explaining how it varies with different salts. Various examples, such as BaSO4, BaF2, and AgCl, are explored to show how to calculate Ksp, solubility, and ion concentrations in saturated solutions, providing clear explanations and worked examples throughout.

Takeaways

• 😀 Salts, such as NaCl, dissolve in water to form ions like Na+ and Cl-, creating a solution known as a saturated solution if the solute reaches its maximum solubility.
• 😀 A saturated solution occurs when the solvent can no longer dissolve additional solute, resulting in the formation of a precipitate.
• 😀 The solubility of salts in water varies. Some salts, like NaCl, are highly soluble, while others, such as BaSO4, are poorly soluble.
• 😀 Solubility is expressed in mol/L (molarity) and refers to the maximum amount of solute that can dissolve in a solvent at a specific temperature.
• 😀 The solubility product (Ksp) is the equilibrium constant that represents the product of the concentrations of ions in a saturated solution.
• 😀 In the case of BaSO4, if the solubility is 1 × 10^-5 mol/L, both Ba²⁺ and SO₄²⁻ ions will have the same concentration of 1 × 10^-5 mol/L in the saturated solution.
• 😀 For salts like BaF2, with a solubility of 1.7 × 10^-6 mol/L, the concentration of F⁻ ions will be twice that of Ba²⁺ because of the stoichiometry in the dissociation reaction.
• 😀 Ksp for salts can be calculated by multiplying the concentrations of the ions raised to their respective coefficients in the dissociation equation.
• 😀 Ksp values are temperature-dependent and can vary with changes in temperature.
• 😀 Solubility and Ksp are closely related: knowing the solubility of a salt allows for the calculation of its Ksp, and vice versa, as demonstrated with examples like PbI2 and CaF2.

Q & A

What happens when NaCl dissolves in water?

When NaCl dissolves in water, it dissociates into sodium ions (Na+) and chloride ions (Cl-). This creates a solution that can initially dissolve more NaCl, forming a saturated solution. If more NaCl is added, the solution becomes supersaturated and precipitation occurs.

What is the difference between a saturated and a supersaturated solution?

A saturated solution contains the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature. A supersaturated solution, however, contains more solute than a saturated solution, which can lead to the formation of a precipitate when additional solute is added.

What is solubility?

Solubility is the maximum amount of a substance that can dissolve in a solvent at a specific temperature, usually expressed in mol/L (molarity). For insoluble substances, solubility is very low.

How does the solubility of NaCl compare to BaSO4?

NaCl is highly soluble in water, meaning it can dissolve in large amounts. In contrast, BaSO4 has very low solubility and forms a precipitate quickly when dissolved in water, even with a small amount.

What is the relationship between solubility and Ksp?

Ksp, or the solubility product constant, represents the equilibrium constant for the dissociation of a slightly soluble salt. The Ksp value helps determine the solubility of the salt. The larger the Ksp, the more soluble the salt is.

How is the Ksp for BaSO4 calculated?

For BaSO4, the Ksp is calculated by multiplying the concentrations of its dissociated ions, Ba2+ and SO4 2-, raised to the power of their respective coefficients. In this case, since both have a coefficient of 1, Ksp = [Ba2+][SO4 2-].

Why does the Ksp of BaSO4 differ from that of BaF2?

The Ksp of BaSO4 is lower than that of BaF2 because BaSO4 is much less soluble in water. The dissociation of BaSO4 into Ba2+ and SO4 2- produces fewer ions compared to BaF2, which dissociates into Ba2+ and two F- ions, leading to a higher Ksp for BaF2.

What happens when the temperature of a solution changes in relation to Ksp?

When the temperature of a solution changes, the value of Ksp can change as well. For most salts, an increase in temperature increases the solubility and therefore the Ksp. However, for some salts, the solubility decreases with higher temperatures.

How do you calculate the solubility of a salt from its Ksp value?

To calculate the solubility of a salt from its Ksp value, you first write the dissociation equation and express the ion concentrations in terms of the solubility (s). Then, substitute the values of the concentrations into the Ksp expression and solve for s.

How do you find the solubility of PbI2 given its Ksp and the solubility in mol/L?

For PbI2, which dissociates into Pb2+ and 2 I-, the Ksp expression is Ksp = [Pb2+][I-]^2. Given the solubility of PbI2 as 1.2 x 10^-3 mol/L, you can calculate the concentration of Pb2+ (1.2 x 10^-3 mol/L) and I- (2.4 x 10^-3 mol/L) and then substitute these into the Ksp expression to find the Ksp.