Question

Hexachlorophene is used as a disinfectant in germicidal soaps. What mass of hexachlorophene (406.9 g/mol) must be added to 125 g of chloroform to give a solution with a boiling point of 62.60°C?

Answer 1

Answer: 18 grams

Step-by-step explanation:

Elevation in boiling point:

`\Delta T_b=i* k_b* m`

`T_b-T^o_b=i* k_b* (w_2* 1000)/(M_2* w_1)`

where,

`T_b` = boiling point of solution =
`62.60^oC`

`T^o_b` = boiling point of chloroform =
`61.2^oC`

`k_b` = boiling point constant of chloroform =
`3.88^oC/m`

m = molality

i = Van't Hoff factor = 1 (for non-electrolyte)

`w_2` = mass of solute (hexachlorophene ) = x g

`w_1` = mass of solvent (chloroform) = 125 g

`M_2` = molar mass of solute (hexachlorophene ) =406.9

Now put all the given values in the above formula, we get:

`(62.60-61.2)^oC=1* (3.88^oC/m)* ((xg)* 1000)/(406.9* (125g))`

`1.40^oC=1* (3.88^oC/m)* ((xg)* 1000)/(406.9* (125g))`

`x=18g`

Therefore, the mass of hexachlorophene that must be added is 18 grams