Heating and Cooling Graphs

• What is internal energy?

  Energy stored inside a system by particles
• What types of energy are included in internal energy?

  Kinetic and potential energy of particles
• What does potential energy depend on in a substance?

  Forces between particles and atomic bonds
• What is the graph called when a solid is heated?

  Heating graph
• What happens to the temperature of a solid as it is heated?

  The temperature rises as energy increases
• What occurs when the temperature stops rising on a heating graph?

  The solid is changing state to a liquid
• What is the term for the process of a solid turning into a liquid?

  Melting
• What is the latent heat?

  Energy needed for a substance to change state
• What does the melting point represent on a heating graph?

  The temperature at which melting occurs
• What happens after all the solid has melted?

  The temperature starts to rise again
• What occurs when the temperature stops increasing again on the heating graph?

  The substance is boiling
• What is the term for the process of a liquid turning into a gas?

  Boiling
• What happens after all the liquid has boiled?

  The temperature starts to rise again
• What is the graph called when a gas is cooled down?

  Cooling graph
• What is the process called when a gas changes to a liquid?

  Condensation
• What is the process called when a liquid changes to a solid?

  Freezing
• What are the key points to interpret heating and cooling graphs?

  • Identify changes of state
  • Recognize melting and boiling points
  • Understand latent heat concept
  • Analyze temperature changes during processes
• What is the significance of the horizontal lines on heating and cooling graphs?

  They indicate a change of state
• How does the energy input affect the state of a substance in heating graphs?

  It weakens forces between particles during state changes