Ferrofluids

The video explores how insoluble substances can appear dissolved through experiments with iron powder and ferrofluid. Iron powder remains insoluble in water and oil but reacts to magnets, revealing magnetic fields. Ferrofluid, a colloid of oil and iron nanoparticles, behaves like a liquid but forms spikes under a magnetic field, demonstrating its unique properties.

What materials are needed to demonstrate how an insoluble substance can appear dissolved?

• Iron powder, Petri dishes, a magnet, and oil

• Iron powder, Petri dishes, a magnet, and sand

• Iron powder, Petri dishes, a magnet, and ferrofluid

• Iron powder, Petri dishes, a magnet, and water

What happens when iron powder is mixed with water and a magnet is placed underneath?

• The iron powder floats on the water surface

• The iron powder dissolves completely

• The iron powder forms a pattern revealing the magnetic field

• The iron powder changes color

How does iron powder behave when mixed with oil and exposed to a magnet?

• It dissolves in the oil

• It reacts to the magnet independently of the oil

• It forms a solid block

• It evaporates

What is ferrofluid composed of?

• Water and iron particles

• Oil and iron nanoparticles

• Sand and iron particles

• Oil and water

Why do the iron nanoparticles in ferrofluid not separate from the oil?

• They are constantly struck by oil molecules, keeping them in motion

• They are heavier than the oil

• They are too large to separate

• They dissolve in the oil

What happens when a magnet is placed under a dish of ferrofluid?

• The ferrofluid becomes solid

• The ferrofluid separates into oil and iron

• The ferrofluid evaporates

• The ferrofluid forms spikes under the influence of the magnetic field

What gives ferrofluid its magnetic properties?

• The suspended iron nanoparticles

• The temperature of the environment

• The water content

• The oil in the mixture