Soap solution is a colloid
Micelles stay apart and scatter light.
A cloudy solution
Soap dissolved in water does not look clear. It looks cloudy, though nothing settles at the bottom.
What do you think keeps the soap micelles from settling out?
What this lesson covers
The idea
Soap micelles stay in solution as a colloid, kept from coming together and precipitating by ion-ion repulsion; they are large enough to scatter light, so a soap solution appears cloudy.
A cloudy solution
Soap dissolved in water does not look clear. It looks cloudy, though nothing settles at the bottom.
What do you think keeps the soap micelles from settling out?
- They repel one another
- They are too small to be seen
- They are heavier than water
Micelles in water
Open every tab.
Why it stays cloudy
The micelles do not clump together and fall to the bottom. They are also big enough to scatter light, which makes the solution look cloudy.
Soap micelles stay in solution as a colloid, kept from coming together and precipitating by ion-ion repulsion. They are large enough to scatter light, so a soap solution appears cloudy.
Notes
Soap micelles stay in solution as a colloid, kept from precipitating by ion-ion repulsion. They are large enough to scatter light, so a soap solution appears cloudy.
Check yourself
What stops soap micelles from coming together and precipitating?
Why does a soap solution appear cloudy?
What kind of mixture do soap micelles form in water?
Which particles scatter light in a soap solution?
- Ion-ion repulsion — correct. Yes!
- They are too heavy to move. The book says ion-ion repulsion keeps the micelles from coming together.
- They are attracted to one another. If they were attracted, they would come together and precipitate. Ion-ion repulsion keeps them apart.
- The soap dissolves into single ions. The micelles are large enough to scatter light, and this is why the solution looks cloudy.
- The micelles are large enough to scatter light — correct. Yes!
- The water is dirty. A soap solution looks cloudy because its micelles scatter light.
- A solid lump. Micelles stay in solution as a colloid and do not precipitate.
- A clear solution with nothing scattering light. The micelles scatter light, so the solution is cloudy.
- A colloid — correct. Yes!
- The micelles — correct. Yes!
- The water molecules. The book says the soap micelles are large enough to scatter light.
- Single sodium ions. The micelles, being large, scatter light.