Solutions Question 403
Question: Boiling point of chloroform was raised by 0.323 K, when 0.5143 g of anthracene was dissolved in 35 g of chloroform. Molecular mass of anthracene is: ( $ K_{b} $ for $ CHCl_3 $ = 3.9 kg/mol )
Options:
A) 79.42 g/mol
B) 132.32 g/mol
C) 177.42 g/mol
D) 242.32 g/mol
Show Answer
Answer:
Correct Answer: C
Solution:
Here: $ \Delta T_{b} $ = 0.323 K w = weight of Anthracene. W = weight of chloroform
$ K_{b} $ = Molal elevation constant (3.9 K-kg/mol)
$ m=\frac{K_{b}\times w\times 1000}{W\times \Delta T_{b}}=\frac{3.9\times 0.5143\times 1000}{0.323\times 35} $
$ =177.42g/mol $
