Enthalpy and Phase Changes

These flashcards cover key concepts related to enthalpy, phase changes, and properties of liquids as discussed in lecture.

What is the process called when a solid turns into a liquid?

Melting or fusion.

What is the enthalpy change associated with melting called?

Heat of fusion.

What do we call the process of a solid turning directly into a gas?

Sublimation.

What is the term for the phase change from a liquid to a gas?

Vaporization or boiling.

What type of process occurs during melting and vaporization?

Endothermic process.

What is the term for the phase change from a gas to a solid?

Deposition.

What do we call the phase change from a gas to a liquid?

Condensation.

What is the term for the phase change from a liquid to a solid?

Freezing.

What kind of signs do you expect for enthalpy changes associated with endothermic processes?

Positive signs.

What does vapor pressure depend on?

Temperature and intermolecular forces.

How does increasing temperature affect vapor pressure?

It increases vapor pressure.

What happens to vapor pressure when intermolecular forces are strong?

Vapor pressure decreases.

What is the boiling point defined as?

The temperature at which vapor pressure equals atmospheric pressure.

What is the water's density relationship between solid and liquid phases?

Liquid water is more dense than solid ice.

What do you call the point where a substance exists in all three phases at once?

Triple point.

What causes surface tension in liquids?

Cohesive forces between liquid molecules.

What is viscosity?

The measure of a fluid's resistance to flow.

What factor can decrease the viscosity of a liquid?

Increasing temperature.

What is capillary action?

The ability of a liquid to flow in narrow spaces without the assistance of external forces.