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ERIC Number: EJ1240818
Record Type: Journal
Publication Date: 2020-Jan
Pages: 6
Abstractor: As Provided
ISSN: ISSN-0021-9584
Stepwise Approach to Hess's Law Using Household Desiccants: A Laboratory Learning Program for High School Chemistry Courses
Kodani, Satoki; Fukuda, Masahiro; Tsuboi, Yoji; Koga, Nobuyoshi
Journal of Chemical Education, v97 n1 p166-171 Jan 2020
This study focuses on designing a laboratory learning program for a high school chemistry course in which students could discover the fundamental principles of Hess's law via stepwise inquiry. By exploring the chemical properties of common desiccants, mainly those that were reactive in water, students were introduced to the exothermic reaction of CaO(s) with H[subscript 2]O(l) as a heating agent. Due to the difficulties associated with directly measuring the heat of reaction for CaO(s) with H[subscript 2]O(l), the heats of reaction for CaO(s) with HCl(aq) and Ca(OH)[subscript 2](s) with HCl(aq) were measured. Students could find the most appropriate experimental procedures through discussion in each group and subsequently establish a protocol in the class. The heats of reaction determined by students' experiments closely corresponded to those calculated using the thermodynamic database. Using the experimental values obtained for the reactions of CaO(s) with HCl(aq) and Ca(OH)[subscript 2](s) with HCl(aq), students could discover the relationship that existed among the heats of reaction for CaO(s) with H[subscript 2]O(l), CaO(s) with HCl(aq), and Ca(OH)[subscript 2](s) with HCl(aq) by drawing an energy diagram and making the relevant thermochemical calculations.
Division of Chemical Education, Inc. and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Research
Education Level: Secondary Education; High Schools
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A