chapter 9!

Internal energy-kinetc energy and potential energy
-Kinetic component is due to the vibration of the particles.
-Potential component is due to stretching and compressing of the intermolecular bonds as the particles vibrate.

Melting is when a solid changes to a lquid due to the temperature change.

1. melting point of ice where the constant temperature at which ice turns into the water(0 degrees celsius)
2. During the change of states from ice to water,there is no change in temperature even tough thermal energy is being absorbed.

Solidification is the change in state from liquid to solid,without a chanfge in temperature. Thermal energy is released by the substance.

Video:

Boiling-reverse of condensation. To determine the boiling point of any substance,continue heating until it boils. It is when a pure liquid is heated and changes to a vapour at a fixed or constant temperature.

How does a liquid boil?

the thermal energy is used to do work to separate the molecules as well as to push back on the surrounding atmosphere. The particles are now further apart with negligible intermolecular forces of attraction between them,thus there is a change in state from liquid to gas.

Evaporation

-Evaporationis like boiling where the change from liquids to gas takes place. However,evaporation can take place at any temperature.

differences between boiling and evaporation-

boiling:-

1. occurs at a fixed temperature
2. quick process
3. takes place throughout the liquid
4. bubbles form in the liquid
5. temperature remains constant
6. thermal energy supplied by energy source

evaporation:-

1. occurs at any temperature
2. slow procce
3. takes place only at the liquid surface
4. no bubbles are formed in the liquid
5. temperature may change
6. thermal energy supplied by the surroundings

evaporation removes thermal energy from surroundings.(eg. water)

how does evaporation occur?

Evaporation of ether takes place at room temperature where energetic molecules are able to escape from the liquid surface.

Application of evaporation

1.evaporation on skin

2.wet clothes dry after a while

3. person with fever can be controlled and kept down trough water

4.the refrigerator keeps the contents in the fridge cold.

FACTORS!

-temperature-higher temperatures increases the rate of evaporation. A warmer liquid has greater number of molecules at the surface layer.

-humidityof surrounding air-rate of evaporation decreases with increasing humidity

surface area of liquid-A larger exposed surface area means more molecules can escape from the liquid.

-movement of air-moving from one's hair dryer removes the molecules of a liquid as oon as they escape from the surface of hair.

-pressure-reducing the atmospheric pressure increases the rate of evaporation

-boiling point of the liquid-liquids with lower boiling point will evaporate faster.

Done! :D