Solutions Question 407

Question: Calculate the weight of non-volatile solute having molecular weight 40, which should be dissolved in 57 g octane to reduce its vapor pressure to 80%:

Options:

A) 47.2 g

B) 5g

C) 106.2g

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

$ P_{s}=( \frac{80}{100} )P^{o},w=- $ $ M_{solute}=40,,w=114g,,M_{solvent}=114 $ $ \frac{P_{{}}^{O}-P_{s}}{P_{s}}=\frac{w\times M_{solvent}}{M_{solute}\times W} $ or $ \frac{P_{{}}^{O}-( 80/100 )P^{O}}{( 80/100 )P^{O}}=\frac{w\times 114}{40\times 57} $

$ \therefore $ $ w=5g $



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