TED-Ed: Why don't oil and water mix? - John Pollard

The video explains why salt dissolves in water while oil does not, focusing on the concepts of energetics and entropy. Energetics involves the attractive forces between molecules, while entropy refers to the randomness of molecular arrangements. Water molecules engage in a hydrogen bonding network, favoring the inclusion of salt ions, which dissolve and integrate into the water. In contrast, oil molecules, due to their size and structure, disrupt the water's molecular dance, leading to their exclusion. The balance of molecular interactions and configurations determines whether substances mix.

What are the two main factors that determine why substances dissolve or not?

• Color and texture

• Volume and density

• Energetics and entropy

• Temperature and pressure

How do energetics influence the solubility of substances in water?

• Through the attractive forces between molecules

• By increasing the volume of the solution

• By altering the color of the solution

• By changing the temperature of the water

What does entropy favor in terms of molecular arrangements?

• Keeping molecules separate

• Decreasing the pressure

• Mixing of molecules

• Increasing the temperature

Why do salt ions remain in the 'dance' with water molecules?

• They are too large to leave

• They add more possible dance positions

• They are heavier than water

• They are repelled by water

What is the main reason oil molecules are not good 'dance partners' with water?

• They are wearing 'gigantic ball gowns'

• They are too light

• They are too similar to water molecules

• They are too small

What happens to oil molecules when they are 'squeezed out' by water?

• They band together and separate from water

• They become part of the water's hydrogen bonding network

• They evaporate

• They dissolve in water

Why do water and oil not mix according to the dance analogy?

• Oil molecules are too similar to water

• Oil molecules are too energetic

• Water molecules are too small

• They don't make great dance partners