Teaching Boyle's Law and Charles' Law through Experiments that Use Novel, Inexpensive Equipment Yielding Accurate Results

Abstract

© 2018 American Chemical Society and Division of Chemical Education, Inc. We discuss the use of a simple piece of equipment made of a 50 mL syringe attached to a 2 mL graduated pipet to demonstrate Boyle's law and Charles's law. A plot of the hydrostatic pressure against the reciprocal of the volume of the gas read from the equipment is linear as discussed in the paper and gives the atmospheric pressure at the y-intercept. A plot of the volume of the gas against the Celsius temperature of the gas is also linear as discussed in the paper and gives the absolute zero at the x-intercept. This plastic "high-precision syringe" is simple, disposable, and inexpensive (<1 USD per set) but can yield a high correlation coefficient (class median r2 ≥ 0.95) and accurate results (class median within 1% from Patm = 101 kPa or within 5 °C from -273 °C). These results are achieved because changes in gas volume are read precisely on the graduated lines of the pipet, and the change is significant because of the amount of gas in the syringe. In addition to the two gas laws, this experiment can also be used to teach glassware scale reading, error analysis, use of a spreadsheet program, and statistical analysis.