# Boiling And Freezing Points

Updated 2009-02-19 12:29

## Overview

In a solution containing a particular solute dissolved in a particular solvent, if msolute is the molality of the solute and i is its van't Hoff factor, then the boiling point for a solution containing that solute rises by:

ΔT=Kbmsolutei

from the boiling point for the pure solvent. Meanwhile, the freezing point for a solution containing the solute falls by:

ΔT=Kfmsolutei

from the freezing point for the pure solvent. The molality for a particular solute is:

msolute=(moles of solute)/(kg of solvent)

and is in units of m=mol/kg. The van't Hoff factor is:

i=(moles of particles in solution)/(moles of solute dissolved).

The expected van't Hoff factor is the number of particles formed when a solute completely dissociates in the solvent. Often the observed van't Hoff factor is slightly lower than the expected van't Hoff factor due to partial dissociation of the solute.

## Tables

Solvent
Boiling
Point
(deg C)
Kb
(deg C kg/mol)
Freezing
Point
(deg C)
Kf
(deg C kg/mol)
Water
(H2O)
100.00.5101.86
Carbon Tetrachloride
(CCl4)
76.55.03-22.9930
Chloroform
(CHCl3)
61.23.63-63.54.70
Benzene
(C6H6)
80.12.535.55.12
Carbon Disulfide
(CS2)
46.22.34-111.53.83
Ethyl Ether
(C4H10O)
34.52.02-116.21.79
Camphor
(C10H16O)
208.05.95179.840

Solution
Boiling
Point
(deg C)
Freezing
Point
(deg C)
18.00g of glucose
(CHO, 180.0g/mol)
in 150.0g of water
100.34-1.24
7.80kg of ethylene glycol
(C2H6O2, 62.1 g/mol)
in 10.0L of water
106.4-23.3
0.10m glucose
in water
100.051-0.186
fully dissociated
0.10m NaCl
in water
100.102-0.372
fully dissociated
0.10m K2SO4
in water
100.153-0.558
fully dissociated
0.10m Fe3(PO4)2
in water
100.255-0.930
fully dissociated
0.20m MgCl2
in water
100.306-1.116
fully dissociated
0.20m MgSO4
in water
100.204-0.744
fully dissociated
0.20m FeCl3
in water
100.408-1.488
fully dissociated
0.35m HCl
in water
100.357-1.302
fully dissociated
0.20m Fe(NH4)2(SO4)2
in water
100.51-1.86

## Reference

Chapter 11 of "Chemistry" by Steven S. Zumdahl, 1986,
D. C. Heath and Company (ISBN=0-669-04529-2).