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Solution Chemistry Calculator

Compute all four colligative properties for any solution. Enter solvent choice, molality, molarity, van't Hoff factor, and temperature to get boiling point elevation, freezing point depression, osmotic pressure, and vapor pressure lowering with step-by-step math.

Solution Parameters

Moles Solute (n_solute)1.000 mol
Moles Solvent (n_solvent)55.50 mol
Mass of Solvent1.00 kg
Volume of Solution1.00 L
Temperature298.1 K
van't Hoff Factor (i)1.00

Solution Properties

Molality
1.0000 mol/kg
Molarity
1.0000 mol/L
X solute
0.01770
X solvent
0.98230
m=nsolutekg solventm = \frac{n_{\text{solute}}}{\text{kg solvent}}
m=11m = \frac{1}{1}
m=1 mol/kgm = 1\,\text{mol/kg}
Boiling Point Elevation
+0.5120 °C
New bp: 100.512 °C
ΔTb=i⋅Kb⋅m\Delta T_b = i \cdot K_b \cdot m
ΔTb=(1)(0.512)(1)\Delta T_b = (1)(0.512)(1)
ΔTb=0.512 ∘C\Delta T_b = 0.512\,^\circ\text{C}
Freezing Point Depression
-1.8600 °C
New fp: -1.860 °C
ΔTf=i⋅Kf⋅m\Delta T_f = i \cdot K_f \cdot m
ΔTf=(1)(1.86)(1)\Delta T_f = (1)(1.86)(1)
ΔTf=1.86 ∘C\Delta T_f = 1.86\,^\circ\text{C}
Osmotic Pressure
24.4662 atm
2479.037 kPa
π=i⋅M⋅R⋅T\pi = i \cdot M \cdot R \cdot T
π=(1)(1)(0.08206)(298.15)\pi = (1)(1)(0.08206)(298.15)
π=24.4662 atm\pi = 24.4662\,\text{atm}
Vapor Pressure Lowering
-0.4212 mmHg
New vp: 23.379 mmHg
ΔP=Xsolute⋅P∘\Delta P = X_{\text{solute}} \cdot P^\circ
ΔP=(0.0177)(23.8)\Delta P = (0.0177)(23.8)
ΔP=0.4212 mmHg\Delta P = 0.4212\,\text{mmHg}
Psolution=P∘−ΔP=23.3788 mmHgP_{\text{solution}} = P^\circ - \Delta P = 23.3788\,\text{mmHg}

Phase Diagram

Dashed lines show the solution; solid lines show pure Water. Colligative properties shift the liquid-gas curve right (higher bp) and the solid-liquid curve left (lower fp).

1 atm050100Temperature (°C)Pressure (atm)bp 100.0°bp 100.5°fp 0.0°fp -1.9°Pure WaterSolution

Reference Guide

What Are Colligative Properties?

Colligative properties depend only on the number of dissolved particles, not their chemical identity. The four main colligative properties are boiling point elevation, freezing point depression, osmotic pressure, and vapor pressure lowering.

All four scale with the van't Hoff factor ii (number of particles per formula unit) and the concentration of dissolved solute.

Ionic compounds like NaCl dissociate into multiple ions (i=2i = 2), amplifying every colligative effect compared to a molecular solute such as sugar (i=1i = 1).

Boiling and Freezing Points

Dissolved solute lowers the vapor pressure of the solvent (Raoult's law). A lower vapor pressure means higher temperature is needed to boil and lower temperature to freeze.

ΔTb=i⋅Kb⋅m\Delta T_b = i \cdot K_b \cdot m
ΔTf=i⋅Kf⋅m\Delta T_f = i \cdot K_f \cdot m

where KbK_b and KfK_f are solvent-specific ebullioscopic and cryoscopic constants, and mm is molality (mol solute / kg solvent).

Osmotic Pressure

Osmotic pressure is the pressure needed to prevent osmosis through a semipermeable membrane. It depends on molarity (mol/L) rather than molality, and directly on temperature.

π=i⋅M⋅R⋅T\pi = i \cdot M \cdot R \cdot T

where R=0.08206R = 0.08206 L atm/(mol K) is the gas constant and TT is absolute temperature in Kelvin. IV saline is formulated to match blood plasma osmotic pressure (~7.5 atm).

The van't Hoff Factor

The van't Hoff factor ii counts the number of particles one formula unit produces in solution.

  • Sugar, glucose, urea: i=1i = 1 (no dissociation)
  • NaCl, KCl, HCl: i=2i = 2 (two ions)
  • CaCl2, MgCl2: i=3i = 3 (three ions)
  • AlCl3: i=4i = 4 (four ions)

Real solutions deviate from ideal values due to ion pairing. These calculator values assume complete dissociation.