One given of a monobasic acid dissolved in 200 g of water lowers the freezing point by 0.186° C. On the other hand, when 1 g of the same acid is dissolved in water so as to make the solution 200 mL, this solution requires 125 mL of 0.1 N NaOH for complete neutralization. Calculate α for the acid in percent. ( K f =1.86 K kg mol -1)

Question

One given of a monobasic acid dissolved in 200 g of water lowers the freezing point by 0.186° C. On the other hand, when 1 g of the same acid is dissolved in water so as to make the solution 200 mL, this solution requires 125 mL of 0.1 N NaOH for complete neutralization. Calculate α for the acid in percent. ( K f =1.86 K kg mol -1) (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

(1/M text acid )=(125/1000) × 0.1 ⇒ M text acid =80 g mol -1 0.186=(1+α) × 1.86 ×[((1/80)/0.2)] ⇒ α=0.6 ⇒ 60 %

Macid ​1​=1000125​×0.1 ⇒Macid ​=80gmol−1 0.186=(1+α)×1.86×[0.2801​​] ⇒α=0.6⇒60%

$\frac{1}{M _{acid}} = \frac{125}{1000} \times 0.1$
$\Rightarrow M_{acid} = 80 g m o l^{- 1}$
$0.186 = (1 + α) \times 1.86 \times [\frac{\frac{1}{80}}{0.2}]$
$\Rightarrow α = 0.6 \Rightarrow 60%$