Phase Changes and Energy Concepts

The lecture explores the phase change of water at constant pressure, focusing on the transition from solid to liquid and liquid to gas. It explains how energy input affects kinetic and potential energy, leading to temperature changes and phase transitions. The concepts of endothermic and exothermic processes are discussed, highlighting the energy changes during melting, freezing, vaporization, and condensation.

What does the x-axis represent in the phase change graph of water?

• Pressure in atm

• Volume in liters

• Energy input in Joules

• Temperature in Celsius

During the phase change from solid to liquid, what happens to the temperature?

• It increases

• It decreases

• It remains constant

• It fluctuates

What type of energy increases when water is heated from 0°C to 100°C?

• Thermal energy

• Chemical energy

• Kinetic energy

• Potential energy

What is the slope of the graph during a phase change?

• Undefined

• Zero

• Negative

• Positive

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

• Melting

• Freezing

• Vaporization

• Condensation

Which process is endothermic: melting or freezing?

• Neither

• Both

• Freezing

• Melting

What is the enthalpy change sign for an exothermic process?

• Negative

• Zero

• Undefined

• Positive

Which phase change releases energy into the environment?

• Vaporization

• Freezing

• Melting

• Sublimation

What happens to the potential energy during a phase change?

• It remains constant

• It decreases

• It increases

• It fluctuates

Which of the following is an exothermic process?

• Melting

• Condensation

• Vaporization

• Sublimation