$word_{count}$: 200

When a solute distributes between two immiscible solvents: K = C$\frac{organic}{C}$(aqueous) = constant at given temperature. If K > 1, compound prefers organic phase → extraction is favorable. Single extraction with V mL organic solvent from W mL water with initial mass m: mass extracted = $\frac{mKV}{W + KV}$. Remaining = $\frac{mW}{W + KV}$. Multiple extractions $\frac{n times with V}{n mL each}$: remaining after n extractions = m[$\frac{W}{W + KV/n}$]^n. Mathematical proof: [$\frac{W}{W + KV/n}$]^n < $\frac{W}{W + KV}$ for n > 1. Therefore multiple small extractions ALWAYS recover more than one large extraction. Practical example: K = 4, 10 g compound in 100 mL water. One extraction with 100 mL ether: extracted = 10(4)$\frac{100}{(100+400)}$ = 8 g (80%). Three extractions with 33.3 mL each: first removes ~5.7 g, second ~2.4 g, third ~1.0 g → total ~9.1 g (91%). Significant improvement with same total solvent. JEE calculations: set up K equation, solve for mass extracted, compare single vs multiple extractions. Always show that n extractions are more efficient.