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 $ .
