Change of state

CHANGE OF STATE

SOLID ENERGY < COHESION

LIQUID ENERGY = COHESION

GAS ENERGY > COHESION

MELTINGBOILING

VAPORIZATION

FREEZING CONDENSATION

SUBLIMATION

DEPOSITION

REMOVING HEAT (COOLING)

ADDING HEAT

MELTINGWhen a solid is heated the particles gain energy and vibrate faster and faster

The sructure is weakened and the particles break free from their fixed positions (having enough energy to overcome the atractions between particles)

MELTING

Each pure substance has a specific BOILING/MELTING POINT (Ex: Water 100ºC, Silver 2162 ºc, Iron 1535ºC)

Temperature remains constant during the change of state

SolidIncreasing Thermal Energy

Melting/freezing point

Liquid

BOILING1. When a liquid is heated the particles move faster

2. The most energènic particles at the scape from the liquid as a vapour

3. The temperature when a solid melts is known as BOILING POINT

4. Temperature is constant while the boiling is taking place.

5. It happens in all the liquid, not just in the surface

Some boiling amb melting examples….

Substance Melting Point (ºC)

Boiling Point (ºC)

Water 0 100

Alcohol - 114 78,5

Oxigen - 218 - 183

Iron 1538 2861

Mercury - 39 357

It takes place only on the surface of the liquid

Some particles in liquids have more energy than others

The more energetic particles take energy from the liquid to become a gas. And the liquid cool down

Evaporation is produced at room temperature (at any temperature)

Examples: puddles (when they get dry), when we get cold after sweeting…

EVAPORATION

canvis d’estat

estats de la matèria

BOILING

EVAPORATION

SUBLIMATION

Matter changes straight from a solid to a gas!

Molecules speed up and spread out rapidly

Examples: Naftalina, dry ice, deodorant