Brilliant bile
Bile is a bitter tasting, dark green to yellow brown fluid.
It is an essential part of digestion and allows the body
to absorb fat.
Production of bile is just one of over 500 functions of the
liver, which is the largest internal organ of the body.
Once the bile is produced it is stored in the gall bladder until
our body needs it.
As partially digested food passes from the stomach to the
small intestine, bile is secreted to aid digestion.
Try our experiment to see what’s going on!
You will need:
 Oil
 Glass jug containing 500ml of water with 4/5 drop of food
colouring added (use any colour except yellow)
 Washing up liquid
 2 bottles with lids
1. Add water to the bottles until they are about ½ full.
2. Add oil to the bottles. The oil will form a layer on top of the water.
3. Add a generous squirt of washing up liquid to one of the
bottles.
4. Put the lids on both bottles and give them a vigorous
shake.
Stand back and enjoy the show
What’s happening…
The bottle with oil and water
begins to separate almost
immediately.
The bottle with oil, water and
washing up liquid stays mixed
for much longer.
Why…
You have made an emulsion, a
mixture of two liquids that are
normally immiscible (unmixable).
Hydrophilic head
Hydrophobic tail
Soap molecules have two ends. One end loves water (hydrophilic) and the other
fears water (hydrophobic). When you add soap to the oil and water the hydrophilic
end bonds to the water and the hydrophobic end bonds to the oil.
Like soap, bile has both hydrophobic and hydrophilic sections. The bile emulsifies
the fat in the partially digested food which increases the surface area of the fats
allowing for easier absorption into the blood stream.