Tpm updated
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Transcript of Tpm updated
Objectives
At the end of the lesson, students should be able to:
• define melting and freezing.
• define boiling and condensation.
• interpret the heating and cooling curve.
Internal energy The internal energy of a body is the combination of the
total kinetic energy (due to molecular motion) and the
potential energy (due to intermolecular forces) of the
molecules in the body.
An increase in temperature leads to an increase in the
kinetic component of the internal energy.
Melting and Freezing
Melting and Freezing Melting is a process in which a substance changes its
state from solid to liquid.
The temperature at which this happens is called the
melting point of the substance.
Solid Liquid
Melting and Freezing Freezing is a process in which a substance changes its
state from liquid to solid.
The temperature at which this happens is called the
freezing point of the substance.
Liquid Solid
Melting point = Freezing point
Boiling and Condensation
Boiling and Condensation Boiling is a process in which a substance changes its
state from liquid state to gaseous state.
The temperature at which this happens is called the
boiling point of the substance.
Liquid Gas
Boiling and Condensation Condensation is a process in which a substance changes
its state from gaseous state to liquid state.
The temperature at which this happens is called the
condensation point of the substance.
Gas Liquid
Boiling point = Condensation point
Take Note! During the change of state
(melting/freezing/boiling/condensation), the
temperature of the substance remains constant.
For example, when pure ice is melting at 0oC, it will
remain at 0oC until the ice has melted completely. The
temperature of pure water will increase beyond 0oC,
when more thermal energy is added to the water.
This is a temperature-time graph. In this example, ice is being heated from -10oC. As you can see, the temperature of ice rises to 0oC.
When the temperature of ice reaches 0oC, the ice melts. During the change in state, there is no change in temperature even though thermal energy is still being transferred to the water.