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Kinetic Molecular Kinetic Molecular TheoryTheory
What do we assume about What do we assume about the behavior of an ideal the behavior of an ideal gas?gas?
Gas molecules are in constant, random motion and when they collide they do not lose energy. Pressure is caused by the collision of gas molecules with their surroundings
The average kinetic energy of gas molecules is proportional to their temperature in Kelvins
Gas molecules are so small compared to the distance between them, they can be considered as having no volume
Gas molecules do not exert attractive of repulsive forces on each other
Are these true for a real Are these true for a real gas?gas?
Gas molecules are in constant, random motion and when they collide they do not lose energy. Pressure is caused by the collision of gas molecules with their surroundings
-Yes: we know molecules move (smells from the kitchen can be detected upstairs), and pressure is observed in all gas situations
The average kinetic energy of gas molecules is proportional to their temperature in Kelvins
Yes: experimentally determined
Gas molecules are so small compared to the distance between them, they can be considered as having no volume- No: when molecules are compressed or - No: when molecules are compressed or
cooled, their volumes can become cooled, their volumes can become significantsignificant
- For example: volumes of liquids and solids- For example: volumes of liquids and solids
Gas molecules do not exert attractive of repulsive forces on each other
-No: again, if compressed or cooled, -No: again, if compressed or cooled, molecules will absolutely attract or molecules will absolutely attract or repel… how do we know?repel… how do we know?
Significance of KMTSignificance of KMT
Helps us predict gas behavior under Helps us predict gas behavior under most conditions of temperature and most conditions of temperature and pressurepressure
Most substances that are gases at 1atm Most substances that are gases at 1atm clearly follow all gas laws as given in the clearly follow all gas laws as given in the ideal gas equationideal gas equation
When do ideal gases When do ideal gases behave as real gases?behave as real gases?
