2 Internal energy

Which change of state? Solid to liquid

• Melting

• Evaporation

• Condensation

• Freezing

Which change of state? Liquid to gas

• Melting

• Evaporation

• Condensation

• Freezing

Which change of state? Gas to liquid

• Melting

• Evaporation

• Condensation

• Freezing

The average kinetic energy of the particles in a substance

• internal energy

• temperature

• heat

• thermodynamics

Heat transfer occurs:

• in many directions
• both from warm objects to colder ones and from cold objects to warmer ones
• only from warm objects to colder ones
• only from cold objects to warmer ones

The temperature of a substance increases as___.

• the substance expands
• the average kinetic energy of its particles increases
• the substance's volume increases
• the substance's mass increases

What is the internal energy of a substance

• The sum of the kinetic and potential energies of the particles

• The kinetic energy of the particles

• The potential energy of the particles

• The speed of the particles

The diagram shows a heating curve. Between which points is the internal energy of the substance greatest?

• A and B

• B and C

• D and E

• E and F

When a substance is heated from 25 ^oC to 50 ^oC,

• its internal kinetic energy decreases.

• its internal potential energy decreases.

• its internal kinetic energy increases.

• its internal potential energy increases.

When a substance is boiling,

• its internal kinetic energy decreases.

• its internal potential energy decreases.

• its internal kinetic energy increases.

• its internal potential energy increases.