Foundations — Solubility product Ksp — common-ion suppression, selective precipitation

2.6.15 · D1 · Chemistry › Equilibrium › Solubility product Ksp — common-ion suppression, selective p

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1. Dissolving asal mein kya hai?

Figure dekho. Orange arrows woh ions hain jo solid chhod rahe hain (dissolving). Blue arrows woh ions hain jo solid pe wapas aa rahe hain (crystallising). Shuruaat mein dissolving tez hoti hai — paani khali aur inviting hota hai. Jaise-jaise paani bharta hai, returning tez hoti jaati hai, jab tak dono rates match nahi karte.

2. Double arrow $\rightleftharpoons$ aur dissolution equation

3. Square brackets $[]$ — concentration

Tumhe concentration mass ya moles aur volume se milti hai — woh machinery stoichiometry and solution concentration hai. Hum ise lagaataar reuse karte hain.

4. Coefficients aur powers $x$, $y$ (aur charges $n$, $m$)

${\text{CaF}}_2$ ke liye: ek calcium aur do fluorides saath aate hain, isliye $x=1$, $y=2$ (jahan $n=2$, $m=1$). Picture hai ek crystal chunk teen pieces mein toot raha hai: 1 Ca aur 2 F.

Figure mein red number-labels dikhate hain ki $y=2$ kyun ek pair ${\text{F}}^{-}$ force karta hai har ek ${\text{Ca}}^{2+}$ ke liye appear hone ke liye. Yeh 1-phir-2 counting har us squared term ka beej hai jo tumhe baad mein dikhai degi.

5. Equilibrium constant $K_c$ — aur kyun solids isse gayab ho jaate hain

Ab dissolving salts ke liye special move:

Ise dissolution par apply karo: $K_c=\frac{[{\text{M}}^{n+}{]}^x[{\text{A}}^{m-}{]}^y}{[{\text{M}}_x{\text{A}}_y(s)]}=\frac{[{\text{M}}^{n+}{]}^x[{\text{A}}^{m-}{]}^y}{1}$

6. Solubility $s$ — measurable cousin

Unka link seedha counting se aata hai (Section 4): agar $s$ mol of ${\text{M}}_x{\text{A}}_y$ dissolve hote hain, toh woh $xs$ mol of ${\text{M}}^{n+}$ aur $ys$ mol of ${\text{A}}^{m-}$ per litre produce karte hain.

$K_{sp}=(xs{)}^x(ys{)}^y=x^x{y}^y{s}^{x+y}$

Figure $K_{sp}$ ko $s$ ke against plot karta hai ek 1:1 salt ke liye (blue, curve $K_{sp}=s^2$) aur ek 1:2 salt ke liye (orange, curve $K_{sp}=4s^3$). Dhyaan do: same $K_{sp}$ par (dashed gray line) dono salts ki alag solubilities hain. Isliye tum kabhi bhi do salts ko sirf $K_{sp}$ se compare nahi kar sakte jab tak woh same $x:y$ shape share nahi karte.

7. Ionic product $Q$ — $K_{sp}$ ka "not-yet-balanced" twin

• Needle line ke neeche ($Q<K_{sp}$): paani thirsty hai — unsaturated, aur dissolve ho sakta hai.
• Needle line par ($Q=K_{sp}$): saturated — Section 1 ka balance.
• Needle line ke upar ($Q>K_{sp}$): hold karna impossible hai — excess solid ke roop mein crash ho jaata hai (precipitate) jab tak needle wapas line par nahi aa jaati.

8. Le Chatelier — woh "push-back" jo suppression drive karta hai

Energy reason kyun equilibria wahan settle hote hain jahan karte hain, Gibbs free energy se belong karta hai; in ideas ke acid–base cousins pH aur pOH mein rehte hain; aur payoff — ek mixed mixture se ek metal ion nikalna — qualitative inorganic analysis hai.

9. Pieces topic ko kaise feed karte hain

Equipment checklist

Answers cover karo aur khud ko test karo. Agar koi bhi line tumhe rok de, parent note kholne se pehle uska section upar phir padho.