The common-ion effect can be applied to a solution of lead thiocyanate when potassium thiocyanate is added. Since there is a common ion, the cyanate ion, the molar solubility of lead thiocyanate goes down in the presence of potassium thiocyanate. Calculate the molar solubility of lead thiocyanate in 0.600 M KSCN.

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ajeigbeibraheem ajeigbeibraheem · Answer 1 · 2020-02-16T18:26:14+01:00

Answer:

5.56 ×10⁻⁵M

Explanation:

The formula for lead thiocyanate = Pb(SCN)₂ and for potassium thiocyanate, we have KSCN.

The standard solubility product [tex]K_{sp[/tex] of Pb(SCN)₂ is known to be 2.0 × 10⁻⁵

Since there are 0.600 M of KSCN, definitely if KSCN dissociates we have:

KSCN ⇄ K⁺ + SCN⁻

0.600M 0.600 M 0.600 M

On the other hand, if Pb(SCN)₂ dissociates ; we have:

Pb(SCN)₂ ⇄ Pb⁺ + 2SCN⁻

x x 0.600 M

[tex]K_{sp[/tex] = x(0.600)²

2.0 × 10⁻⁵ = x (0.36)

x = [tex]\frac{2.0*10^{-5}}{0.36}[/tex]

x = 5.56 × 10⁻⁵ M

∴ The Molar Solubility of lead thiocyanate in 0.600 M KSCN = 5.56 × 10⁻⁵ M