RP08 - Boyle's + Charles' Laws

• State Boyle's Law

  • When kept at a constant temperature, the pressure and volume of a gas are inversely proportional
  • pV = constant
• State Charles' Law

  • When kept at a constant pressure, the absolute temperature and volume of a gas are directly proportional
  • V/T = Constant
• How would you go about measuring the cross-sectional area of the inside of a syringe?

  • Remove the plunger and then, using a micrometer, measure the diameter of the seal
  • This value can then be substituted into the circular area equation
• Why should the clip used to seal the tubing, coming from the syringe, be as close to the syringe tip as possible?

  The volume of air trapped in the tubing should be as small as possible so that it is negligible in comparison to the volume in the syringe
• Suggest how a mass hanger could be attached to the plunger of the syringe

  • A small piece of string can be tied to the plunger to form a loop
  • The hanger can then hook onto this loop
• Why should the syringe be clamped above the region of the plunger's motion?

  • Clamping the syringe can distort the barrel and hinder the motion of the plunger
  • By clamping above the region in which the plunger moves, this problem is avoided
  • It also ensures that the scale on the syringe isn't covered by the clamp
• Why should the syringe be clamped at a relatively high position?


  The syringe should be clamped at a height so that the plunger jas space to move downwards as masses are added
• State the value of atmospheric pressure

  101 kPa
• Describe the relationship that should be founded when a graph 1/V against P is plotted

  • Pressure and volume are inversely proportional
  • The graph of 1/V against P should be a straight line that passes through the origin
• Suggest why a straight line may not be produced when plotting a graph of 1/V against P

  • The plunger may have experienced some resistance to its motion as masses were added
  • This sticking of the plunger would create an error that may result in an inaccurate measured change in volume
• What safety precautions should be taken when using concentrated sulphuric acid?

  • Safety goggles should be worn to ensure that no acid enters your eyes
  • Gloves could also be worn to ensure that there is no contact between the acid and your skin
• What safety precautions should be taken when working with a hot beaker of water?

  • Avoid touching the hot beaker with bare hands and ensure that it is handled with care to avoid spillages
  • A heatproof mat should be used to protect the bench
• What should you do before recording each measurement of water temperature?

  You should always stir the water before taking a temperature measurement so that the reading is an appropriate and accurate reflection of the average temperature of the water in the beaker