Gases. Matter forms, Gases uses & Gases reactions. Matter exists mainly in 3 states: _Solid (definite shape and volume) _Liquid (definite shape, but indefinite volume) _Gas (indefinite shape and indefinite volume). Matter forms, Gases uses & Gases reactions.
Matter exists mainly in 3 states:
_Solid (definite shape and volume)
_Liquid (definite shape, but indefinite volume)
_Gas (indefinite shape and indefinite volume)
Matter composing particles move according to the matter state in which they are found, thus:
_Liquid (vibration + rotation)
_Gases (vibration + rotation + translation)
*This theory is called Kinetic Theory of Gases
*This behavior is observed when pressure is applied to a gas (compressed gas)
Diffusion: Natural tendency of gases to spread in space
*At the same temperature, lighter molecules diffuse faster than heavier molecules
Olfaction (sense of smell): Allows us to perceive odours when the gaseous molecules get in contact with olfactory receptors
Odours and Toxicity are not directly related. Thus, we can have very toxic odourless molecules (e.g. CO) or some smelly ones with no serious effect to our health (e.g. skunk spray)
Brownian motion: Random motion exhibited by atomic particles as they constantly move
*Dogs have 100-200 millions olfactory cells, humans only 5 millions
Phase change: Transition from one state to another (e.g. solid to liquid)
During phase changes, T remains constant as the energy provided is used to overcome the attraction between the molecules
Boiling is related to Pressure. Thus, the lower the external pressure, the faster the boiling (less energy required), therefore lower boiling point or boiling temperature
As temperature increases, the motion of particles increase, and the result is an increment of the number of collisions among said particles.
The raise of temperature thus produces an Expansion in the case of solids and liquids
The drop of temperature produces a Contractionin the case of solids and liquids
Applications of expansion/contraction: thermometers
The absorption of heat during vaporization (liquid – gas phase change) is the basic principle of refrigerators and cooling appliances.
Refrigerant liquid absorbs heat off food and ambient air inside the refrigerator in order to change into a gas, thus cooling the environment.
CFC’s (e.g. Freon) as Refrigerants
HFC’s are preferred over CFC’s (ozone layer)
Atmosphere: Protective layer that sustains life.
CO (silent killer):