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QJEEM22Ch96e8: JEE Main 2022 Chemistry - Class 12 JEEM22Ch96e8 Solution: When a certain amount of solid A is dissolved in 100   g…

When a certain amount of solid A is dissolved in 100 g of water at 25∘C to make a dilute solution, the vapour pressure of the solution is reduced to one-half of that of pure water. The vapour pressure of pure water is 23.76mmHg. The number of moles of solute A added is _____________. (Nearest Integer)

Step-by-Step Verified Solution

∵\because Diliute solution given:

P0−PSP0∼n solute n solvent 

P0−P0/2P0=n solute n solvent 

n{ }^{\mathrm{n}} solute ∼n solvent 2=10018×2=2.78 mol\sim \frac{{ }^{\mathrm{n}} \text { solvent }}{2}=\frac{100}{18 \times 2}=2.78 \mathrm{~mol}

More accurate approach:

P0−PSPS=n solute n solvent 

P0−P0/2P0/2=n solute n solvent 

n{ }^n solute =n={ }^n solvent =10018=5.55 mol=\frac{100}{18}=5.55 \mathrm{~mol}

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