Question

The qualitative sketches I, II and III given below show the variation of surface tension with molar concentration of three different aqueous solutions of KCl, CH₃OH and CH₃ (CH₂)₁₁ OSO\(^-_3\) Na⁺ at room temperature. The correct assignment of the sketches is

(A) I: KCI  II: CH₃OH  III: CH₃(CH₂)₁₁ OSO\(^-_3\) Na⁺

(B) I: CH₃ (CH₂)₁₁ OSO\(^-_3\) Na⁺  II: CH₃OH  III: KCI

(C) I: CH₃ (CH₂)₁₁ OSO\(^-_3\) Na⁺  II: CH₃OH  III: KCI^-

(D) I: CH₃OH  II: KCI III: CH₃(CH₂)₁₁ OSO\(^-_3\) Na⁺

Answer 1

(D) I : CH₃OH  II : KCI III: CH₃(CH₂)₁₁ OSO\(^-_3\) Na⁺

Strong electrolytes like KCl increase the surface tension slightly. Low molar mass organic compounds usually decrease the surface tension. Surface active organic compounds like detergents sharply decrease surface tension