Hydrophilic and Hydrophobic Surfaces

The video explores the behavior of water on hydrophobic and hydrophilic surfaces, explaining the concepts of contact angles and the polar nature of water. It demonstrates practical applications, such as removing permanent markers and spray paint using hydrophilic surfaces. Experiments with ferrofluid and attempts to create a super hydrophobic surface are also shown.

What is one potential application of super hydrophilic surfaces mentioned in the video?

• Producing non-stick cookware

• Creating waterproof clothing

• Developing self-cleaning windows

• Making walls resistant to spray paint

What contact angle with water defines a surface as hydrophobic?

• Between 30° and 60°

• Exactly 90°

• Greater than 90°

• Less than 5°

Which natural surface is mentioned as being super hydrophobic?

• Kale leaves

• Cactus spines

• Rose petals

• Lotus leaves

What happens to a drop of water on a super hydrophilic surface?

• It bounces off the surface

• It forms a perfect sphere

• It flattens out completely

• It evaporates quickly

Why is water able to remove permanent marker from a super hydrophilic surface?

• Water slides under the marker

• Water is non-polar

• The surface is heated

• The marker dissolves in water

What is the main challenge in removing spray paint from a hydrophilic surface?

• The paint is non-polar

• The paint is too thick

• The paint is water-soluble

• The paint sinks into the surface

What is ferrofluid described as in the video?

• A light, foamy material

• A clear, oily fluid

• A dark, nonviscous liquid

• A thick, sticky substance

What happens when water is poured on ferrofluid on a hydrophilic surface?

• The ferrofluid solidifies

• The ferrofluid floats to the top

• The ferrofluid evaporates

• The ferrofluid mixes with water

What was the result of applying a super hydrophobic coating on the surface?

• The surface repelled all liquids

• The surface became completely hydrophobic

• The surface remained super hydrophilic

• The surface became a super normal surface

What is the purpose of using fumed silica in the experiment?

• To make surfaces hydrophilic

• To increase the surface's temperature

• To clean the surface

• To create a super hydrophobic coating