A General Chemistry laboratory experiment has been developed that uses the ideal gas law to determine the molar mass of an unknown carbonate by allowing the carbonate to react with an aqueous 1 M HCl solution to produce CO2 gas. The volume, temperature and pressure of the evolved CO2 gas are measured. Good choices for the unknown carbonate are the environmentally friendly compounds NaHCO3, CaCO3 and K2CO3, which have a suitable range of molar masses. This experiment uses commonly available reagents and equipment and produces non-hazardous waste. Only very small quantities of reagents are used. This experiment produces a non-toxic gas (CO2) and so does not require the use of a fume hood. The experiment illustrates the ideal gas law, conversions involving temperature, volume and pressure and Dalton’s Law of Partial Pressures. In this experiment, two trials can easily be performed in one laboratory period.

Laboratory experiment: Carbonates and the ideal gas law

249th National Meeting (2015)

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