In model 1 phase changes shown are:
D = freezing/solidification
E = Fusion/melting
F= Boiling
G= Condensation
Explanation:
Key answers:
1. Addition of energy
E arrow is showing the fusion or melting of solid into a liquid. The tightly packed molecules of the solid will require energy to move faster. The kinetic energy provided will increase the movement of molecules by breaking bonds between them.
Boiling requires energy. In the process of boiling when energy is provided to the liquid particles, they move faster away from each other. At one time the free particles would escape as a gas.
Condensation requires heat energy to change its state from gas to liquid. Say the water molecules are evaporated in the air, they cool down and condense to be in the liquid state.
2. When energy is provided to the system by the surrounding or external means it is called an endothermic reaction.
3. Release of energy:
D is the process of condensation which will give out energy due to the difference in the energy level of liquid and solid particles. As energy will be removed for the freezing of the molecules to be compact. This process is exothermic.
4. When energy is released into the surrounding by the system it is called an exothermic reaction.
