How to Find out whether a Precipitation of a Salt May Happen under Certain Conditions – Part 1

Solubility equilibrium is a type of dynamic equilibrium that exists when a solid chemical compound is in chemical equilibrium with a solution of that compound.


The solid may dissolve unchanged, with dissociation, or with chemical reaction with another component of the solution, viz., acid, base or salt. Each solubility equilibrium is characterized by a temperature-dependent solubility product which functions like an equilibrium constant.

Question:

A solution contains 0.2 M Ba2+ & 0.2 M Ca2+. What CrO42– concentration will precipitate as much Ba2+ as possible without precipitating any CaCrO4? Ksp of BaCrO4 = ~1 × 10-10 & Ksp of CaCrO4 = ~7 × 10−4

Solution:



Click to enlarge the image

A saturated CaCrO4 solution will leave the Ca2+ ions in solution, but will overwhelm the Ba2+ ions (the difference of 6 orders of magnitude (10−4 versus 10−10) tells it).

Stimulated by the idea of solubility product❓ Let Chemaficionado know at mychemistryhomework@gmail.com❗

References:

(1)    Wikipedia Contributors. Solubility equilibrium. Wikipedia. https://en.wikipedia.org/wiki/Solubility_equilibrium.

‌(2)    Ncert. Chemistry : Textbook for Class XI - Part.I; National Council Of Educational Research And Training: New Delhi.

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