The Microscale Determination of the Molar Mass of Metals Using a Gas-Pressure Sensor

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

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Abstract Volume 9 Issue 6 (2004) pp 364-365

The Microscale Determination of the Molar Mass of Metals Using a Gas-Pressure Sensor

James Gordon,* Amber Boyce, and Thoren Maule

Division of Science and Mathematics, Central Methodist University, Fayette, MO 65248, jgordon@centralmethodist.edu
Received September 9, 2004. Accepted October 31, 2004.

Published online: 16 November 2004

Abstract. Many metals react with mineral acids to produce hydrogen gas. In this work, small amounts, less than 0.100 g, of manganese and zinc were individually reacted with hydrochloric acid to produce hydrogen gas in known stoichiometric ratios. The pressure of the hydrogen gas generated was measured using a gas-pressure sensor. The gas pressure was used to determine the moles of hydrogen gas produced and, ultimately, the moles of metal reacted. Using the mass and moles of the metals, the average molar masses of manganese and zinc were determined to be 54.3 ± 2.5 g mol^–1 and 62.4 ± 2.9 g mol^–1, respectively.

Key Words: Laboratories and Demonstrations; general chemistry; introductory chemistry; high school chemistry; metals; molar mass; microscale; redox reactions; calculator-based learning; gases

(*) Corresponding author. (E-mail: jgordon@centralmethodist.edu)

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