Considering acetic acid dissociates in water, its dissociation constant is (6.25 10⁻⁵ ). If (5 ~mL ) of acetic acid is dissolved in 1 litre water, the solution will freeze at (-x 10⁻² ^ C ), provided pure water freezes at (0^ C ). (x= ) ______ . (Nearest integer) Given : ( aligned & ( K _f )_ water =1.86 ~K ~kg ~mol ⁻¹ . & density of acetic acid is 1.2 ~g ~mol ⁻¹ . & molar mass of water =18 ~g ~mol ⁻¹ . & molar mass

Step-by-step solution

aligned & Mass of CH ₃ COOH = V d & =5 ml 1.2 ~g / ml & =6 gm & n _ CH ₃ COOH = 6 60 =0.1 ~mol & ~m _ CH ₃ COOH M _ CH ₃ COOH = 0.1 1 =0.1 M & CH ₃ COOH CH ₃ COO ⁻+ H ⁺ aligned C aligned & C - C C C & K _ a = C ^2 1- & 1- 1 K _ a = C ^2 & = Ka C = 6.25 10⁻⁵ 0.1 =25 10⁻³ aligned aligned & V.f. ( i )=1+ ( n -1)=1+ (2-1)=1+ & =1+25 10⁻³=1.025 & T _ f = i K _ f m & =(1.025)(1.86)(0.1) & =0.19 & =19 10⁻² aligned