1. Increased Kinetic Energy:
* Heat is energy: When you add heat to acetone, you're essentially adding energy to its molecules. This energy increases the kinetic energy of the molecules.
* Molecules move faster: Increased kinetic energy means the acetone molecules start moving faster and vibrating more intensely.
2. Weakening Intermolecular Forces:
* Van der Waals forces: Acetone molecules are held together by relatively weak intermolecular forces called Van der Waals forces.
* Breaking bonds: As the molecules move faster, they overcome these weak forces more easily. This weakens the attraction between them.
3. Phase Change:
* Evaporation: As the intermolecular forces weaken, some acetone molecules gain enough energy to escape the liquid surface and enter the gas phase. This is evaporation.
* Boiling point: At a specific temperature (the boiling point of acetone, which is 56°C), the vapor pressure of the acetone becomes equal to the atmospheric pressure, and the liquid boils rapidly.
4. Increased Vapor Pressure:
* More gas molecules: As the temperature increases, more and more acetone molecules evaporate, increasing the number of acetone molecules in the gaseous state.
* Higher vapor pressure: This increase in gas molecules leads to a higher vapor pressure, which is the pressure exerted by the gas molecules above the liquid.
5. Acetone Expansion:
* Volume increases: The increased kinetic energy of the molecules causes them to move further apart, leading to an expansion in the volume of the acetone.
Summary:
Heating a beaker of liquid acetone increases the kinetic energy of the molecules, weakens the intermolecular forces, causing evaporation and ultimately, boiling. The vapor pressure increases, and the acetone expands.
