Solutions Question 390

Question: A compound has the empirical formula $ C_{10}H_8Fe $ . A solution of 0.26 g of the compound in 11.2 g of benzene $ (C_6H_6) $ boils at $ 80.26{}^\circ C $ . The boiling point of benzene is $ 80.10{}^\circ C $ and $ K_{b} $ is $ 2.53{}^\circ C/molal. $

What is the molecular formula of the compound-

Options:

A) $ C_{30}H_{24}Fe_3 $

B) $ C_{10}H_8Fe $

C) $ C_5H_4Fe $

D) $ C_{20}H_{16}Fe_2 $

Show Answer

Answer:

Correct Answer: D

Solution:

$ \Delta T_{b}=80.26 $ $ 0.16=2.53\times \frac{0.26/M}{11.20}\times 1000; $

$ M\approx 367 $ This is almost equal to molar mass of $ C_{20}H_{16}Fe_2 $ .



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