Changes in State
Kinetic and Potential Energy
Kinetic Energy is the energy an object has due to its motion.
The faster particles move, the more kinetic energy they have.
Temperature is a measure of the average kinetic energy of all the particles in an object.
As the temperature increases, the particles usually have more kinetic energy.
Potential Energy is stored energy due to the interactions between particles or objects.
Potential energy typically increases when objects get farther apart and decreases when they get closer together.
The chemical potential energy of particles increases and decreases as the distances between particles increase or decrease.
Thermal Energy is the total potential and kinetic energies of an object.
You can change an object's state of matter by adding or removing thermal energy.
Adding thermal energy can increase the speed of the particles (increase kinetic energy) or increase the distance between them (increases potential energy.)
The opposite is true when you remove thermal energy. If enough thermal energy is added or removed, a change of state can occur.
Solid to Liquid or Liquid to Solid
The Aluminum Recycling Process
Step 1: Melting
By adding thermal energy to the aluminum, we can increase the temperature of the aluminum until it reaches the melting point of which it then melts. While it is melting, the temperature doesn't increase (however, energy changes still occur,) and it turns into liquid.
Energy Change: When a solid melts into a liquid, its temperature doesn't change, but the energy changes. This is because the particles don't speed up, but they move farther apart. Then after it melts, they start to speed up because of the thermal energy.
Step 2: Freezing
After the aluminum melts, it is poured into molds to cool. Freezing is the opposite of melting and there is a freezing point. As the aluminum cools, the thermal energy leaves it.
Liquid to Gas or Gas to Liquid.
The change from liquid to gas is called vaporization. There are two types of vaporization called evaporation and boiling.
Boiling
Evaporation
Boiling occurs when thermal energy is added to water until it reaches its boiling point, which then the particles move farther apart until they no longer have any attractive force.
If thermal energy continues to be added, then after it becomes a gas, the temperature keeps increasing.
Evaporation is vaporization that only occurs at the surface of a liquid.
Condensation
Condensation is when gas turns into liquid because it looses too much thermal energy.
Solid to Gas or Gas to Solid
Sublimation is the change of state of matter from solid to gas without turning into a liquid.
Deposition is the change of matter from gas to solid without turning into a liquid.
Example: as water vapor loses thermal energy, it becomes frost.
Example: Dry Ice becomes gas when thermal energy is applied to it.
States of Water
Water is the only substance that exists in its solid, liquid, and gas form within Earth's temperature range.
By adding thermal energy to ice, at 0°C Ice becomes water, and at 100°C water becomes vapor. The backwards is also possible by removing thermal energy.
Matter and Energy conservation
When matter changes state, the matter and energy are conserved.