NTA Abhyas JEE Main2020ChemistrySolutionsPractice
Depression in freezing point of 0.01 molal aqueous HCOOH solution is 0.02046°C. 1 molal aqueous urea solution freezes at –1.86°C. Assuming molality equal to molarity, calculate the pH of HCOOH solution.
Correct answer
3.00
Step-by-step solution
1.86 = K f (1) 0.02046 = (1 + α ) × 1.86 × 0.01 ⇒ 1 + α = 0 . 0 2 0 4 6 0 . 0 1 8 6 = 1 . 1 ⇒ α = 0.1 [H + ] = C α = 0.01 × 0.1 = 10 –3 so, pH = 3.