JEE Main · 2022 · 29 Jun 2022 · Shift 1 · Solutions

WhatsApp Email

1.2 mL of acetic acid is dissolved in water to make 2.0 L of solution. The depression in freezing point observed for this strength of acid is

0.019 8^{\circ} C

. The percentage of dissociation of the acid is ______. (Nearest integer)
[Given: Density of acetic acid is

1.02 g mL^{- 1}

Molar mass of acetic acid is

60 g mol^{- 1}

K_{f} (H_{2} O) = 1.85 K kg mol^{- 1}

]

Answer: 5

Solution

Mass of acetic acid

= d \times V = 1.02 \times 1.2 = 1.224 g

Moles

= \frac{1.224}{60} = 0.0204

moles in 2 L (≈ 2 kg) of water.

Molality

m = \frac{0.0204}{2} = 0.0102 mol/kg

Using

Δ T_{f} = i \times K_{f} \times m

, where

i = 1 + α

for a weak acid:

0.0198 = (1 + α) \times 1.85 \times 0.0102

1 + α = \frac{0.0198}{1.85 \times 0.0102} = 1.0493

α = 0.0493 \approx 5%

JEE Main · 2022 · 29 Jun 2022 · Shift 1 · Integer answer

Practise more: all JEE Main PYQs on Solutions →

More JEE Main questions on Solutions

Elements P and Q form two types of non-volatile, non-ionizable compounds PQ and $PQ_{2}$ . When 1 g of PQ is dissolved in 50 g of solvent 'A', $Δ T_{b}$ was 1.176 K while when 1 g of $PQ_{2}$ is dissolved in 50 g of solvent 'A', …
JEE Main 2026View solution →
Consider a solution of $CO_{2} (g)$ dissolved in water in a closed container.

Which one of the following plots correctly represents variation of log (partial pressure of CO2 in vapour phase above water) [y-axis] with log (mole fraction of $CO_{2}$ …
JEE Main 2026View solution →
Given below are two statements:

Statement I: The Henry's law constant $K_{H}$ is constant with respect to variations in solution's concentration over the range for which the solutions is ideally dilute.
Statement II : $K_{H}$ does not diff …
JEE Main 2026View solution →
The osmotic pressure of a living cell is 12 atm at 300 K. The strength of sodium chloride solution that is isotonic with the living cell at this temperature is $____$ $g L^{- 1}$ . (Nearest integer)

Given: …
JEE Main 2026View solution →
A substance 'X' (1.5 g) dissolved in 150 g of a solvent 'Y' (molar mass $= 300 g mol^{- 1}$ ) led to an elevation of the boiling point by 0.5 K. The relative lowering in the vapour pressure of the solvent 'Y' is $____$ $\times 1 0^{- 2}$ . (Nearest integer)
[Giv …
JEE Main 2026View solution →
Which one of the following graphs accurately represents the plot of partial pressure of $CS_{2}$ vs its mole fraction in a mixture of acetone and $CS_{2}$ at constant temperature ?
JEE Main 2026View solution →