Changes of States Flashcards
How does heat change a state?
When a solid/liquid is heated, the particles gain energy and will vibrate faster until they have enough energy to break away from the forces of attraction and their fixed positions.
When a solid/liquid is cooled, the particles lose energy and will vibrate slower until the particles and molecules cannot overcome the forces of attraction and they get stuck their fixed positions.
Explain “vaporisation.”
When a liquid state changes into a gas, vaporisation takes place.
There are two types of vaporisation: evaporation and boiling.
Boiling occurs throughout the liquid but only at the boiling point - this is the temperature at which the atmospheric pressure equals the vapor pressure of a liquid.
Evaporation always takes place from the surface of the liquid, therefore energy is removed. The particles near the surface have enough energy to overcome the forces of attraction holding the liquid molecules together and it moves into the space above the liquid.
Explain “condensation”.
When a gas state changes into a liquid, condensation takes place: a gas is cooled to its boiling point and below.
Explain “melting”.
When a solid state changes into a liquid, melting takes place. The temperature at which a substance melts is its melting point.
Explain “freezing”.
When a liquid state changes into a solid, freezing takes place. The temperature at which a substance freezes is its freezing point.
Explain “sublimation”.
When a solid state changes directly into a gas, without going through the liquid phase, sublimation takes place.
Explain “deposition”.
When a gas state changes directly into a solid, without going through the liquid phase, deposition takes place.
Name 3 uses of the changes of states.
- Test the purity of a substance.
- Test for mixtures.
- Identify unknown substances.
What is “Brownian Motion”?
Brownian motion is the random motion of particles suspended in a fluid (liquid/gas) resulting from their collision with fast moving atoms/molecules in the gas/liquid.
Define “diffusion”.
Diffusion is the movement and mixing of particles, from a high concentration to a lower concentration.
