At 35°C, the vapour pressure of CS2, is 512 mm Hg and that of acetone is 144 mmHg. A solution of CS2 in acetone has a…
Solutions · Class 12 · JEE Main Previous Year Question
At 35°C, the vapour pressure of , is 512 mm Hg and that of acetone is 144 mmHg. A solution of in acetone has a total vapour pressure of 600 mmHg. The false statement amongst the following is:
- a
Raoult's law is not obeyed by this system
- b✓
a mixture of 100 mL and 100 mL acetone has a volume < 200 mL
- c
and acetone are less attracted to each other than to themselves
- d
heat must be absorbed in order to produce the solution at 35°C
a mixture of 100 mL and 100 mL acetone has a volume < 200 mL
Strategy:\n> Compare the actual measured total pressure (600 mm Hg) with the individual pure vapour pressures (144 and 512 mm Hg). If the total pressure exceeds the highest individual pressure, the system shows extreme positive deviation from Raoult's Law.\n\nStep 1: Identify the deviation type\nThe total pressure (600) is greater than both (512) and (144).\nThis indicates positive deviation.\n\nStep 2: Evaluate statement (2)\n"The volume of a mixture... has a volume < 200 mL".\nIn systems with positive deviation, A–B attractions are weaker than pure state attractions. Molecules push away from each other, leading to a volume increase ().\nThus, the volume will be greater than 200 mL. Statement (2) is false.\n\n
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