Could somone name two changes of state, and describe what causes each to occur.?

Question

Thanks for the help; I just need to understand this.

Answer 1

Melting:
1. When a solid is heated, the heat energy goes to the molecules within the lattice arrangement of the solid.
2. The heat makes the molecules to vibrate about their positions more and more.
3. Eventually strong forces between the molecules (those that hold them in the rigid lattice) are overcome, and the molecules start to move around --> the change of state, i.e. MELTING occurs.

Boiling:
1.When the liquid gets hot enough, virtually all the molecules have enough speed and energy to overcome the forces and escape each other.
2. At this point big bubbles of gas form inside the liquid as the molecules break away from each other. --> This is BOILING

The direct answer to your question as to what causes changes of state to occur - is the input of heat energy. It is all about the ability of molecules either vibrate about their positions (solids), freely move past each other but sticking together (liquids) or travel in straight lines in random motion, interacting with each other only during collisions (gas).

In case of condensing and freezing changes of state, unlike in melting and boiling, heat is given out as the bonds form.

Answer 2

Theres' melting and freezing.
Melting:
The heat energy supplied to the particles of the solid increases the kinetic energy of the particles.As a result the particles start vibrating about their fixed positions.At the melting point of the solid, the solid particles have enough energy to overcome the strong forces of energy binding them together and they separate to form smaller particles of a liquid.
Freezing:
When the liquid is cooled, the kinetic energy of its particles decreases and the particles start drawing closer to each other.Ultimately they get close enough to be converted into a solid and only vibrate about their fixed positios.

Answer 3

there's boiling and condensing.
boiling is when liquid turns to gas, with more heat.
and condensing is when gas turns into liquid... with less heat.