CBSE 2024 · Region 5 · Set 1 · Q32 · 5 marks
(i)Ishan's automobile radiator is filled with $\displaystyle 1.0$ kg of water. How many grams of ethylene glycol (Molar mass $\displaystyle =62 \mathrm{~g} \mathrm{~mol}^{-1}$ ) must Ishan add to get the freezing point of the solution lowered to - $\displaystyle 2.8$ °C. $\displaystyle \mathrm{K}_{\mathrm{f}}$ for water is $\displaystyle 1.86 \mathrm{~K} \mathrm{~kg} \cdot \mathrm{~mol}^{-1}$.(ii)What type of deviation from Raoult's law is shown by ethanol and acetone mixture ? Give reason.(i)Boiling point of water at $\displaystyle 750$ mm Hg pressure is $\displaystyle 99.68^{\circ} \mathrm{C}$. How much sucrose (Molar mass $\displaystyle =342 \mathrm{~g} \mathrm{~mol}^{-1}$ ) is to be added to $\displaystyle 500$ g of water such that it boils at $\displaystyle 100$ °C ? ( $\displaystyle \mathrm{K}_{\mathrm{b}}$ for water $\displaystyle =0.52 \mathrm{~K} \mathrm{~kg}$ $\displaystyle \left.\mathrm{mol}^{-1}\right)$.(ii)State Henry's law and write its any one application.
(i)
Ishan's automobile radiator is filled with $\displaystyle 1.0$ kg of water. How many grams of ethylene glycol (Molar mass $\displaystyle =62 \mathrm{~g} \mathrm{~mol}^{-1}$ ) must Ishan add to get the freezing point of the solution lowered to - $\displaystyle 2.8$ °C. $\displaystyle \mathrm{K}_{\mathrm{f}}$ for water is $\displaystyle 1.86 \mathrm{~K} \mathrm{~kg} \cdot \mathrm{~mol}^{-1}$.
(ii)
What type of deviation from Raoult's law is shown by ethanol and acetone mixture ? Give reason.
(i)
Boiling point of water at $\displaystyle 750$ mm Hg pressure is $\displaystyle 99.68^{\circ} \mathrm{C}$. How much sucrose (Molar mass $\displaystyle =342 \mathrm{~g} \mathrm{~mol}^{-1}$ ) is to be added to $\displaystyle 500$ g of water such that it boils at $\displaystyle 100$ °C ? ( $\displaystyle \mathrm{K}_{\mathrm{b}}$ for water $\displaystyle =0.52 \mathrm{~K} \mathrm{~kg}$ $\displaystyle \left.\mathrm{mol}^{-1}\right)$.
(ii)
State Henry's law and write its any one application.
Marking-scheme solution
(i)
\(\displaystyle \Delta \mathrm{T}_{\mathrm{f}}=2.8^{\circ} \mathrm{C}\)
\[\begin{aligned}
& \Delta \mathrm{T}_{\mathrm{f}}=\mathrm{K}_{\mathrm{f}} \times \mathrm{W}_{\mathrm{B}} / M_{\mathrm{B}} \times \mathrm{W}_{A}(\mathrm{~kg}) \\
& 2.8=1.86 \times w_{\mathrm{B}} / 62 \times 1 \\
& \mathrm{W}_{\mathrm{B}}=(2.8 \times 62) / 1.86
\end{aligned}
\]
\(\displaystyle \mathrm{W}_{\mathrm{B}}=93.33 \mathrm{~g}\)
(ii)
Positive deviation
Interaction between ethanol-ethanol is stronger than ethanol-acteone.
SolutionsColligative Properties and Determination of Molar MassApplylong_answermedium
More from Solutions
- 0.3 g of acetic acid (M=60 g mol^-1) dissolved in 30 g of benzene shows a depression in freezing point equal…2023 · asked 6×
- Define molal depression constant. How is it related to enthalpy of fusion? OR What type of deviation is shown…2024 · asked 3×
- When a liquid and its vapour are at equilibrium and the pressure is suddenly decreased:2026 · asked 3×
- Shweta mixed two liquids A and B of 10 mL each. After mixing, the volume of the solution was found to be 20 ·…2025 · asked 3×
- Explain the following with the help of Henry's law: (i) Bends (ii) Anoxia OR How does sprinkling of salt help…2026 · asked 3×
- Calculate the vapour pressure of a solution containing 61 g of benzoic acid (molar mass =122 g mol^-1 )…2026 · asked 3×
- The boiling point of one molal NaCl solution, assuming NaCl to be completely dissociated in water is: (K b.…2026 · asked 3×
- Give reasons: Cooking is faster in pressure cooker than in an open pan. On mixing liquid X and liquid Y,…2025 · asked 3×
CBSE Class 12 Chemistry past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.