# What is the molar mass of a non-electrolyte compound if 4.28 grams is dissolved in 25.0 grams of chloroform solvent to form a solution which has a boiling point elevation of 2.30 degrees celsius?

## The boiling constant of chloroform is 3.63 degrees Celsius/m im not sure if this is needed but molar mass of chloroform = 119.38 g/mol I need a step by step explanation please.

Mar 27, 2017

The molar mass is 270 g/mol.

#### Explanation:

The formula for boiling point elevation ΔT_"b" is

color(blue)(bar(ul(|color(white)(a/a)ΔT_"b" = K_"b"bcolor(white)(a/a)|)))" "

where

${K}_{\text{b}}$ = the molal boiling point elevation constant of the solvent
$b \textcolor{w h i t e}{m}$ = the molality of the solution

We can rearrange the formula to get

b = (ΔT_"b")/K_"b"

ΔT_"b" = "2.30 °C"
${K}_{\text{b" = "3.63 °C·kg·mol"^"-1}}$

b = (2.30 color(red)(cancel(color(black)("°C"))))/(3.63 color(red)(cancel(color(black)("°C")))·"kg·mol"^"-1") = "0.6336 mol·kg"^"-1"

You have 4.28 g of compound in 0.0250 kg solvent.

;: b = "0.6336 mol"/(1 color(red)(cancel(color(black)("kg")))) = "4.28 g"/("0.0250" color(red)(cancel(color(black)("kg"))))

Divide both sides of the equation by $0.6336$.

$\text{1 mol" = "4.28 g"/0.0250 × 1/0.6336 = "270 g}$

The molar mass is 270 g/mol.