Changes of state

• What is conserved during a change of state?

  Mass
• What is the definition of the melting point?

  The temperature at which a solid changes into a liquid
• What is the definition of the boiling point?

  The temperature at which a liquid turns into a gas
• Why is a change of state considered a physical change?

  Because the changes can be reversed
• If water boils and turns into steam, what happens when that steam touches a cold surface?

  It becomes water
• What is the change of state called when a solid turns into a liquid?

  Melting
• What is the change of state called when a liquid turns into a solid?


  Freezing
• What is the change of state called when a liquid turns into a gas?


  Boiling
• What is the change of state called when a gas turns into a liquid?

  Condensation
• Why does the mass remain the same during a change of state?

  Because the number of particles does not change
• If an ice cube melts, what can you say about the number of particles in the resulting water?

  They are the same as in the solid ice cube
• What is latent heat?

  Energy needed to change a substance's state
• How does the temperature of a substance behave during a change of state?

  The temperature remains constant until the change is complete
• At what temperature does ice melt into water?

  0°C
• At what temperature does water boil into steam?

  100°C
• How can you tell that water is changing state when heated?

  The temperature remains constant during the change
• What is the purpose of plotting a temperature-time graph during a change of state?

  To find the temperature at which the substance changes state
• What change of state occurs when steam from a shower turns to water on a bathroom mirror?

  Condensation
• What change of state occurs when snowflakes turn into water?

  Melting
• If a student measures the temperature of a solid substance every 30 seconds while heating it, what are they trying to determine?

  The temperature changes during the heating process
• How can you use the results from a temperature-time graph to find the melting point of a substance?

  By identifying the temperature at which the substance changes from solid to liquid
• What is the significance of latent heat in a change of state?

  It is the energy required to change the state of a substance without changing its temperature
• Why does the temperature of a substance remain constant during a change of state?


  Because the energy is used to change the state rather than increase the temperature
• What are the specific temperatures for the melting and boiling points of water?

  Melting point is 0°C and boiling point is 100°C
• How would you plot a temperature-time graph for a substance being heated?

  By placing temperature on the y-axis and time on the x-axis