Question

A 135 g sample of carbon disulfide requires 43.2 kj of heat to vaporize completely. what is the enthalpy of vaporization for carbon disulfide?

a. 1.77 kj/mol
b. 24.4 kj/mol
c. 76.2 kj/mol
d. 0.320 kj/mol
e. 3.13 kj/mol

Answer 1

Molecular weight of CS2 = 76.14 g

number of moles of CS2 =
`(weight.of.CS2)/(molecular.weight)`
=
`(135)/(76.14)`
= 1.773

Now, 1.733 mol requires 43.2 kj of heat to vaporize.
∴ 1 mol will require
`(43.2)/(1.77)` = 24.4 kj/mol

Thus, correct answer is option B