charles' law

• equipment

  • capillary tube
  • sulphuric acid
  • 2 litre beaker
  • 2 elastic bands
  • 30cm ruler
  • thermometer
  • kettle
• method

  • set up apparatus with open end of capillary tube at top
  • add hot water from kettle covering air sample
  • stir water using thermometer and record temperature and length of air sample
  • allow water to cool by 5 degrees and repeat taking measurements every 5 degrees down to room temperature
• graphs and calculations

  • plot graph of length against temperature and draw line of best fit
  • absolute zero = $\theta-\frac{l}{m}$
  • $l=$$m\theta+$$c\ \ \rightarrow\ \ c=$$l-m\theta$
  • at absolute zero, length is 0
  • $0=$$m\theta+$$c\ \ \rightarrow\ \ \theta-\frac{l}{m}$
• safety

  • concentrated sulphuric acid can damage eyes
  • boiling water can cause burns

  precautions

  • wear safety goggles
  • wear gloves and be careful pouring water
• improvements

  • tube needs to be perfectly clean to prevent thread of sulphuric acid from splitting