SCIENCE - BEHAVIOR OF GASES

• Robert Boyle


  the English scientist who made accurate observations on the relationship of pressure and volume
• Temperature 


  Constant when using the Boyle’s Law
• Pascal (Pa)


  SI standard unit of pressure
• Correctly represents the relationship between pressure and the volume of an ideal gas that is held at constant temperature

  
• 1 atm = 101,325 Pa
• The volume is inversely proportional to its pressure
• P1V1 = P2V2 


  mathematical statement of Boyle’s Law
• the volume of the gas decreased as the pressure exerted on it increased
• Pressure is the force exerted by the gas on the walls of its container divided by the surface area of the container.
• 1 torr = 1 mm Hg
• Volume is the space occupied. The volume of the gas is equal to the  volume of the vessel or container
• Temperature is the degree of hotness or coldness
• The standard temperature is 0 ⁰C or 273.15 K
• 1 atm = 76 cm Hg
• 1 atm = 760 mm Hg
• 1 atm = 760 torr
• P1V1 = P2V2 is Boyle's Law
• Gas particles have a very weak intermolecular force of attraction, hence they move as far as possible from each other. They have the tendency to occupy all the spaces they are contained in. If the pressure is increased, the volume will be decreased forcing the gas particles to move closer to one another.
• The volume of a gas is inversely proportional to its pressure, if temperature and amount of a gas are held constant. This was stated by Robert Boyle
• The pressure of a gas is the force exerted by the gas on the walls of its container divided by the surface area of the container.
• Pascal is the standard unit of pressure. 101,325 Pa is equivalent to 1 atm or 760 torr
• Boyle's Law is important when using a syringe. When fully depressed, the syringe is at a neutral state with no air in the cylinder. When the plunger is pulled back, you are increasing the volume in the container and thus reducing the pressure
• As pressure decreases, volume increases
• Volume


  The amount of space occupied by a substance
• Temperature


  A measure of the average kinetic energy of the particles in a substance
• When the temperature of a fixed amount of gas increases, its volume increases
• When the temperature of a fixed amount of gas decreases, its volume decreases
• Relationship between temperature and volume of a fixed amount of gas

  1. As temperature increases, volume increases

  2. As temperature decreases, volume decreases
• The relationship between temperature and volume of a fixed amount of gas is known as Charles' Law
• Solid


  Particles are very close to each other and move in a fixed position
• Liquid


  Particles are able to vibrate about their fixed position. Thus, attractions between them are very strong
• Gas

  Particles are far apart and move freely
• Liquid


  The random motion of the particles and their freedom to slide against each other result in weaker forces of attraction. It assumes the shape of the containers. However, the volume is definite
• Gas


  Particles have very weak forces of attraction between them and account for their unique properties
• Properties of Solids, Liquids, and Gases

  • Fixed shape
  • Fixed volume
  • Very high density
  • Difficult to compress
  • Takes the shape of the container
  • Very low density
  • Easily compressed
  • Same volume as container
  • Rapid diffusion
  • No diffusion
• When we talk about gases, they have no definite shape and size, while mass and volume are not directly measurable. The kinetic theory of gases is useful and can be applied in this case.
• Kinetic theory of gases explains the three macroscopic properties of a gas in terms of the microscopic nature of atoms and molecules making up the gas.
• Usually, physical properties of solids and liquids can be described by their, size, shape, mass, volume etc.
• In your previous lessons, you have taken into account three properties of gases, namely, pressure, volume and temperature. These properties along with the kinetic molecular theory of gases will play a significant role in helping you understand the physical properties of gases at the molecular level.
• Gases can be compressed; hence they can occupy a small space