Does benzene dissolve in water?

2 Answers
Nov 16, 2015




different polarities = different solubility parameters

Dec 20, 2015


That depends on your definition of solubility.


The solubility of benzene in water is 1.79 g/L (about 0.02 mol/L) at 15 °C.

So benzene has some solubility in water.

But many chemists set the high/low solubility cut-off point at about 0.10 mol/L.

By that definition, benzene is insoluble in water.

The question then is, "Why is benzene relatively insoluble in water?"

Quick answer: Like dissolves like.

Benzene is nonpolar and water is highly polar.

If we add benzene to water, benzene will float on the top of the water with no apparent mixing.

I couldn't find an image that uses benzene, but here's one that involves hexane, another nonpolar liquid.

The attractive forces among the benzene molecules are relatively weak London dispersion forces.

The attractive forces among the water molecules are relatively strong hydrogen bonds.

The only attractive forces among the benzene and water molecules are London forces.

Thus, a few benzene molecules will enter the water layer, but the strong hydrogen bonds among the water molecules keeps most of the benzene molecules out.

Similarly, a few water molecules will enter the hexane layer because of the water-hexane London forces.

But, for the most part, water and benzene are immiscible. They do not dissolve in each other.