Practical Chemistry

Experiment 9: Determining the relative molecular mass of a gas


To measure the relative molecular mass of a series of gases by direct means


The students have studied the gas laws and are provided with three bottles each containing a different gas.

Instructions given

Plan a method to find out the relative molecular mass of each gas.


Access to the usual laboratory apparatus, balance, barometer, table of temperature-dependent water densities, thermometer.

Experimental report

The following factors will be checked:

  • Choice of method
  • Accurate recording of raw data
  • Presentation of raw data
  • Data analysis and presentation
  • Evaluation of errors both qualitative and numerical


previous page
Copyright: 2003 Isis Publication