Candidate Support Pack - Scottish Qualifications Authority

The diagram below shows a droplet of oil on a fibre submerged in water.
When detergent is added, the molecules try to put their heads in water and their tails in oil.
The only place they can achieve this is on the droplet of oil connected to the fibre.
As the surface of the oil becomes covered with detergent molecules, the molecules begin
to attach themselves to the point where the oil and fibre are joined, and therefore weaken
this joint.
Eventually the connection between the oil and fibre is broken and the oil is lifted off into
the water.
It was mentioned in the section on hard water that water hardness affects this process.
Firstly, it will destroy some of the detergent and, secondly, it will coat the oil with a hard
shell almost immediately and make it more difficult for the detergent molecules to attach
themselves.
GC8N 22 — Laundry Operations Level 2 5.25