Solubility Product Constant: Ksp quiz #1 Flashcards
Solubility Product Constant: Ksp quiz #1
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Which expression can be used to calculate the solubility of CaCO3?
The Ksp expression for CaCO3 is Ksp = [Ca2+][CO3^2-]. To calculate solubility, set [Ca2+] = [CO3^2-] = s, so Ksp = s^2, where s is the molar solubility. What is the solubility of La(IO3)3 in water if its Ksp is 7.5 × 10^-12?
Let the solubility of La(IO3)3 be s. It dissociates as La(IO3)3 → La^3+ + 3 IO3^-. So, [La^3+] = s and [IO3^-] = 3s. Ksp = [La^3+][IO3^-]^3 = s × (3s)^3 = 27s^4. Set 27s^4 = 7.5 × 10^-12 and solve for s: s = (7.5 × 10^-12 / 27)^(1/4) ≈ 5.6 × 10^-4 M. What is the solubility of PbF2 in water if its Ksp is 3.6 × 10^-8?
Let the solubility of PbF2 be s. PbF2 → Pb^2+ + 2 F^-. [Pb^2+] = s, [F^-] = 2s. Ksp = [Pb^2+][F^-]^2 = s × (2s)^2 = 4s^3. Set 4s^3 = 3.6 × 10^-8 and solve for s: s = (3.6 × 10^-8 / 4)^(1/3) ≈ 2.1 × 10^-3 M. C2D3 has a solubility product constant (Ksp) of 9.14 × 10^-9. What is the molar solubility of C2D3?
Assume C2D3 dissociates as C2D3 → 2 C^+ + 3 D^-. Let s be the solubility. [C^+] = 2s, [D^-] = 3s. Ksp = [C^+]^2 [D^-]^3 = (2s)^2 × (3s)^3 = 4s^2 × 27s^3 = 108s^5. Set 108s^5 = 9.14 × 10^-9 and solve for s: s = (9.14 × 10^-9 / 108)^(1/5) ≈ 1.1 × 10^-2 M. What is the solubility of CaF2 (Ksp = 4.0 × 10^-11) in 0.030 M NaF?
CaF2 → Ca^2+ + 2 F^-. In 0.030 M NaF, [F^-] = 0.030 M. Let s be the solubility of CaF2. Ksp = [Ca^2+][F^-]^2 = s × (0.030)^2 = 4.0 × 10^-11. Solve for s: s = 4.0 × 10^-11 / (0.030)^2 ≈ 4.4 × 10^-8 M. Express Ksp in terms of molar solubility.
For a salt AxBy that dissociates as AxBy → x A^y+ + y B^x-, let s be the molar solubility. Then, [A^y+] = x s, [B^x-] = y s. Ksp = [A^y+]^x [B^x-]^y = (x s)^x × (y s)^y = x^x y^y s^(x+y). Why can Ksp values only be directly compared for compounds that dissociate into the same number of ions?
Direct comparison is valid only when compounds dissociate into the same number of ions because the number of ions affects the relationship between Ksp and solubility, making comparisons otherwise misleading. What does the variable 'M' represent in the context of solubility product constant calculations?
'M' stands for molar solubility, which is the maximum amount of a solid that can dissolve in a solvent to reach equilibrium. Why are solids and liquids excluded from the Ksp equilibrium expression?
Solids and liquids are excluded because their concentrations do not change during the reaction and are considered constant, so only the concentrations of dissolved ions are included in Ksp. What is the role of an ICE chart in Ksp calculations?
An ICE chart helps organize initial concentrations, changes, and equilibrium concentrations of ions, which are necessary for solving Ksp-related problems.