gases n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Gases PowerPoint Presentation
Download Presentation
Gases

Loading in 2 Seconds...

play fullscreen
1 / 24

Gases - PowerPoint PPT Presentation


  • 93 Views
  • Uploaded on

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.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Gases' - egan


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
matter forms gases uses gases reactions
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 reactions1
Matter forms, Gases uses & Gases reactions

Matter composing particles move according to the matter state in which they are found, thus:

_Solid (vibration)

_Liquid (vibration + rotation)

_Gases (vibration + rotation + translation)

matter forms gases uses gases reactions3
Matter forms, Gases uses & Gases reactions

Ideal Gases

  • Particles are very small and mainly molecules
  • Particles represented by dots (distance among them much higher than their size)
  • Particles are in continuous motion
  • No attraction forces (independent particles)
  • Kinetic energy of particles a function of their temperature

*This theory is called Kinetic Theory of Gases

matter forms gases uses gases reactions4
Matter forms, Gases uses & Gases reactions

Real Gases

  • Particles are very small and mainly molecules
  • Particles cannot be represented by dots (distance among them comparable to their size)
  • Particles are in continuous motion
  • Attraction forces no longer negligible
  • Kinetic energy of particles a function of their temperature

*This behavior is observed when pressure is applied to a gas (compressed gas)

matter forms gases uses gases reactions5
Matter forms, Gases uses & Gases reactions

Diffusion: Natural tendency of gases to spread in space

(translation motion)

*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

matter forms gases uses gases reactions6
Matter forms, Gases uses & Gases reactions

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

matter forms gases uses gases reactions7
Matter forms, Gases uses & Gases reactions

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

matter forms gases uses gases reactions8
Matter forms, Gases uses & Gases reactions

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

Vaporization Heat

Melting Heat

matter forms gases uses gases reactions9
Matter forms, Gases uses & Gases reactions

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

matter forms gases uses gases reactions10
Matter forms, Gases uses & Gases reactions

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.

matter forms gases uses gases reactions11
Matter forms, Gases uses & Gases reactions

CFC’s (e.g. Freon) as Refrigerants

Pros

  • Odourless
  • Non-toxic
  • Chemically inert

Cons

  • Last too long
  • Reach stratosphere
  • Attacks ozone layer (Cl acts as catalyst of O3 decomposition)

HFC’s are preferred over CFC’s (ozone layer)

matter forms gases uses gases reactions12
Matter forms, Gases uses & Gases reactions

Atmosphere: Protective layer that sustains life.

  • Provides oxygen for respiration
  • Brings water to continents
  • Moderates temperature fluctuations
  • Protects against radiation (ozone layer)
matter forms gases uses gases reactions13
Matter forms, Gases uses & Gases reactions

Troposphere:

  • 80% of atmosphere’s total mass
  • Contains ALL atmosphere's water

Stratosphere:

  • ~20% of atmosphere’s total mass
  • Contains Ozone layer
matter forms gases uses gases reactions14
Matter forms, Gases uses & Gases reactions

Greenhouse effect:

  • Keeps average planet’s temperature
  • Enhanced by GHG’s (greenhouse gases) effect
  • Main contributors H2O & CO2
  • CO2 can be produced naturally or as a result of man’s actions
  • Man-made CO2 contributes to Global Warming
matter forms gases uses gases reactions15
Matter forms, Gases uses & Gases reactions

Environmental role of different gases

matter forms gases uses gases reactions16
Matter forms, Gases uses & Gases reactions

Environmental role of different gases

matter forms gases uses gases reactions17
Matter forms, Gases uses & Gases reactions

Environmental role of different gases

matter forms gases uses gases reactions18
Matter forms, Gases uses & Gases reactions

Respiration:

  • Provides body with oxygen
  • Expels carbon dioxide produced by cells
  • Takes place in both lungs and cells
  • Blood carries gases to and from the tissues
  • Affected by air pollution
matter forms gases uses gases reactions19
Matter forms, Gases uses & Gases reactions

Pollution:

  • Decreases air quality
  • Man-made (industrialization)
  • Produced by emissions of CO, CO2, NOx, SO2 and unburned hydrocarbons
matter forms gases uses gases reactions20
Matter forms, Gases uses & Gases reactions

CO (silent killer):

  • Odourless, colourless
  • Competes with oxygen during gas exchange in respiration
  • Hemoglobin has a greater affinity for CO than for O2
  • CO-filled lungs lack O2
  • Lack of O2 leads to death (asphyxia)
matter forms gases uses gases reactions21
Matter forms, Gases uses & Gases reactions

Gases applications:

Transportation

  • Hot air balloons and dirigibles (hot air expands, therefore less dense, ascension is possible)
  • Airplanes (air flows around plane wings)