Dettol in water - an oil in water emulsion
Juliet
We did an experiment in chemistry today (we are studying surface chemistry,
you see) where by dettol was added to water. It went from being a slightly
transparent, brownish clear type o/w emulsion, to an opaque, whitish,
cloudy liquid. My chem teacher said that it's because the droplets of oil
in the water are now larger because more water has been added. when
detergent was added, more surfactants were added and the oil droplets were
then apparently smaller so the liquid returned to it's normal clearish
state. I asked my chemistry teacher why the larger drops formed when the
dettol was diluted in water, and he didn't know. Does anyone out there in
the world of chemistry have an idea as to why the oil droplets become
bigger causing the liquid to become cloudy?
Juliet Holwill
Melbourne, Australia
--
Hol...@melbpc.org.au
Stewart Rowe
Tom Miller
Isn't "Dettol" just alcoholic PCMX? (p-chlorometaxylenol). If so, the
haze on dilution is more likely the precipitation of the water-insoluble
phenol upon dilution of the alcohol, since the solvency for PCMX decreases
with increasing water content of the alcohol/water mixture.
dmond
"Juliet" <Hol...@melbpc.org.au> wrote:
>We did an experiment in chemistry today (we are studying surface chemistry,
>you see) where by dettol was added to water. It went from being a slightly
>transparent, brownish clear type o/w emulsion, to an opaque, whitish,
>cloudy liquid. My chem teacher said that it's because the droplets of oil
>in the water are now larger because more water has been added. when
>detergent was added, more surfactants were added and the oil droplets were
>then apparently smaller so the liquid returned to it's normal clearish
>state. I asked my chemistry teacher why the larger drops formed when the
>dettol was diluted in water, and he didn't know. Does anyone out there in
>the world of chemistry have an idea as to why the oil droplets become
>bigger causing the liquid to become cloudy?
>
>Juliet Holwill
>Melbourne, Australia
>--
Loss of transparency in emulsions can be caused by collapse of
micellular structure, introduction of heat above the cloud point of
the surfactant which causes a loss of water solubility of the ethylene
oxide portion of the surfactants employed, or collison and growth of
oil solubilized in micelles due to Brownian motion. Most of these
mechanisms will result in separation of the hydrophobe from the
aqueous phase (i.e. cream rising to the top of whole milk).
I'm assuming that by Dettol you mean 3,5-dimethyl-4-chlorophenol. In
this case your initial change of appearance is probably due to its
limited solubility in water. Depending on the detergent or surfactant
used to disperse the Dettol in water you can change the dispersion
from opaque to transparent and from opalescent to yellow in cast.
>Hol...@melbpc.org.au
>
To respond by e-mail just leave off the no.spam and delete the x's
sanjudev...@gmail.com
> We did an experiment in chemistry today (we are studying surface chemistry,
> you see) where by dettol was added to water. It went from being a slightly
> transparent, brownish clear type o/w emulsion, to an opaque, whitish,
> cloudy liquid. My chem teacher said that it's because the droplets of oil
> in the water are now larger because more water has been added. when
> detergent was added, more surfactants were added and the oil droplets were
> then apparently smaller so the liquid returned to it's normal clearish
> state. I asked my chemistry teacher why the larger drops formed when the
> dettol was diluted in water, and he didn't know. Does anyone out there in
> the world of chemistry have an idea as to why the oil droplets become
> bigger causing the liquid to become cloudy?
>
> Juliet Holwill
> Melbourne, Australia
> --
it is because, detergent is an emulsifying agent, and the job of emulsifying agent is to form an inter-facial film between suspended particles and the medium, thereby enhancing the mixing capacity of the two liquids.