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QJEEM24Chfd6a: JEE Main 2024 Chemistry - Class 12 JEEM24Chfd6a Solution: The solution from the following with highest depression in…

The solution from the following with highest depression in freezing point/lowest freezing point is

Multiple Choice Options

  • A 180 g180 \mathrm{~g} of acetic acid dissolved in benzene
  • B 180 g180 \mathrm{~g} of acetic acid dissolved in water
  • C 180 g180 \mathrm{~g} of benzoic acid dissolved in benzene
  • D 180 g180 \mathrm{~g} of glucose dissolved in water

Step-by-Step Verified Solution

ΔTf\Delta \mathrm{T}_{\mathrm{f}} is maximum when i×m\mathrm{i} \times \mathrm{m} is maximum.

1) m1=18060=3,i=1+α\mathrm{m}_1=\frac{180}{60}=3, \mathrm{i}=1+\alpha

Hence

\Delta \mathrm{T}_{\mathrm{f}}=(1+\alpha) \cdot \mathrm{k}_{\mathrm{f}}=3 \times 1.86=5.58^{\circ} \mathrm{C}(\alpha<<1)

2) m2=18060=3,i=0.5,ΔTf=32×kf′=7.68∘C\mathrm{m}_2=\frac{180}{60}=3, \mathrm{i}=0.5, \Delta \mathrm{T}_{\mathrm{f}}=\frac{3}{2} \times \mathrm{k}_{\mathrm{f}}{ }^{\prime}=7.68^{\circ} \mathrm{C}

3) m3=180122=1.48,i=0.5,ΔTf=1.482×kf′=3.8∘C\mathrm{m}_3=\frac{180}{122}=1.48, \mathrm{i}=0.5, \Delta \mathrm{T}_{\mathrm{f}}=\frac{1.48}{2} \times \mathrm{k}_{\mathrm{f}}{ }^{\prime}=3.8^{\circ} \mathrm{C}

4) m4=180180=1,i=1,ΔTf=1⋅kf′=1.86∘C\mathrm{m}_4=\frac{180}{180}=1, \mathrm{i}=1, \Delta \mathrm{T}_{\mathrm{f}}=1 \cdot \mathrm{k}_{\mathrm{f}}{ }^{\prime}=1.86^{\circ} \mathrm{C}

As per NCERT, kf′(H2O)=1.86 k⋅ kg mol−1\mathrm{k}_{\mathrm{f}}{ }^{\prime}\left(\mathrm{H}_2 \mathrm{O}\right)=1.86 \mathrm{~k} \cdot \mathrm{~kg} \mathrm{~mol}^{-1}

kf′( Benzene )=5.12 k⋅ kg mol−1\mathrm{k}_{\mathrm{f}}{ }^{\prime}(\text { Benzene })=5.12 \mathrm{~k} \cdot \mathrm{~kg} \mathrm{~mol}^{-1}

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