Question

section vocabulary
boiling the conversion of a liquid to a vapor when the vapor pressure of the liquid equals the atmospheric pressure
change of state the change of a substance from one physical state to another
condensation the change of state from a gas to a liquid
evaporation the change of state from a liquid to a gas
melting the change of state by which a solid becomes a liquid by adding heat
sublimation the process in which a solid changes directly into a gas

1. describe how do the motions of the particles differ between the states of matter?
2. describe what happens to energy during a change of state? why is it a physical change?
3. describe what are the differences between freezing and melting? how are they similar?
4. explain how are evaporation and boiling the same? how do they differ?
5. describe and compare what is needed for a solid to sublime and what change of state occurs? how does sublimation differ from condensation?
6. complete fill in the missing boxes in the table below.

property	solid	liquid	gas
distance between particles	close	close
movement of particles		they can move past each other

Explanation:

Answer:

(1) In solids, particles vibrate in fixed positions. In liquids, particles move past each other. In gases, particles move freely and rapidly in all directions.
(2) Energy is either absorbed or released during a change of state. It is a physical change because the chemical composition of the substance does not change; only the physical state changes.
(3) Differences: Freezing is the change from liquid to solid, releasing energy. Melting is the change from solid to liquid, absorbing energy. Similarities: They are opposite processes related to the solid - liquid state change and involve energy transfer at a specific temperature (melting/freezing point).
(4) Same: Both are processes of changing from liquid to gas. Different: Boiling occurs throughout the liquid when the vapor pressure equals the atmospheric pressure at a specific temperature. Evaporation occurs at the surface of the liquid at any temperature.
(5) For a solid to sublime, it needs to be at a temperature and pressure where the solid can directly turn into a gas without passing through the liquid state. Sublimation is a solid - gas change, while condensation is a gas - liquid change.
(6)

Property	Solid	Liquid	Gas
distance between particles	close	close	far apart
movement of particles	vibrate in fixed positions	they can move past each other	move freely and rapidly in all directions