Mod 1

• Boyle's Law


  Relationship between volume and pressure at constant temperature of a gas
• Boyle's Law


  Investigate the relationship between volume and pressure at constant temperature of a gas
• In the previous activities, we have discussed the concepts of Boyle's Law, its definition, units, examples and other applications in daily situations
• Applications of Boyle's Law

  • Automobile engine
  • Transport vehicles
  • Drinking soda through a straw
  • Water pump
• Quantities to describe a gas sample

  • Number of moles (amount of matter present (n)
  • Temperature (T)
  • Volume (V)
  • Pressure (P)
• Initial condition


  Represented by subscript 1
• Final condition


  Represented by subscript 2
• Solving Boyle's Law problems

  1. Identify known and unknown values

  2. Apply Boyle's Law equation P1V1 = P2V2

  3. Substitute known values and solve for unknown
• As volume decreases, pressure increases
• As volume increases, pressure decreases
• Boyle's Law graph


  • Hyperbolic curve
  • Inverse relationship between pressure and volume
  • Asymptotes
• Making a line graph

  1. Identify independent and dependent variables

  2. Determine variable range

  3. Determine scale

  4. Number and label axes

  5. Draw curve/line of best fit
• Pressure x Volume is constant for a fixed amount of gas at constant temperature
• Boyle's Law


  Relationship between pressure and volume of a gas at constant temperature
• The pressure-volume graph represents an inverse relationship, as pressure increases, volume decreases
• The relationship is not linear, the line in the graph is curved, and it is not a straight line
• P x V is a constant
• A graph of V against 1/P should be a straight line with a slope (or gradient) equal to the value of the constant
• Making a Cartesian Diver to investigate Boyle's Law

  1. Get an empty plastic soda bottle

  2. Remove labels

  3. Fill bottle with water to the top

  4. Put a small pea-size piece of modelling clay at the end of a pen cap

  5. Slowly place the pen cap into the bottle

  6. Screw the bottle cap on tightly

  7. Squeeze the bottle hard - the pen cap sinks

  8. Stop squeezing and the pen cap rises
• Squeezing the bottle increases the air pressure, compressing the air bubbles in the pen cap and making them denser than the water, causing the pen cap to sink
• When you stop squeezing, the bubble gets bigger again and the water is forced out of the cap, causing the pen cap to rise
• This experiment demonstrates the inverse relationship between pressure and volume as described by Boyle's Law