Phase Changes and Diagrams Concepts

Dr. Mandis explains phase diagrams and heating curves, focusing on the relationship between pressure and temperature. The video covers plotting phase diagrams, understanding phase boundaries, and key points like the triple and critical points. It also discusses heating and cooling curves, emphasizing energy changes during phase transitions.

What does a phase diagram primarily represent?

• The relationship between energy and time

• The relationship between mass and volume

• The relationship between volume and temperature

• The relationship between pressure and temperature

What happens at the boundary lines in a phase diagram?

• No phase change occurs

• Temperature decreases

• Only one phase is present

• Both phases coexist

What is the triple point in a phase diagram?

• Where no phase change occurs

• Where only gas and liquid phases coexist

• Where all three phases coexist

• Where only solid and liquid phases coexist

What is the critical point in a phase diagram?

• The point where solid turns to liquid

• The point where liquid turns to gas

• The point where a supercritical fluid forms

• The point where gas turns to solid

During a phase change, what happens to the temperature of a substance?

• It decreases

• It fluctuates

• It increases

• It remains constant

What role do intermolecular forces play during a phase change?

• They are broken

• They are created

• They are strengthened

• They remain unchanged

In a heating curve, what happens to potential energy as temperature increases?

• It decreases

• It fluctuates

• It increases

• It remains constant

How does a cooling curve differ from a heating curve?

• Temperature increases in a cooling curve

• No phase change occurs in a cooling curve

• Potential energy decreases in a cooling curve

• Kinetic energy increases in a cooling curve

What is the main difference between melting and freezing in terms of energy?

• Both processes release energy

• Freezing releases energy, melting absorbs energy

• Both processes absorb energy

• Melting releases energy, freezing absorbs energy

What remains constant at the plateaus of a heating or cooling curve?

• Pressure

• Kinetic energy

• Potential energy

• Temperature