Microwave Superheating through Attempts at Chemical and Physical Facilitation of Nucleation

Overview

Objectives/Goals The objective of this study was to understand how different physical properties and chemical agents affect microwave superheating of water. Since scientific literature has not fully addressed the interactions and dynamics of this phenomenon, and microwave superheating is not well understood, the hope is that this study will contribute towards better understanding of this phenomenon Methods/Materials Using the same domestic microwave oven set to "normal" power, several samples in 125ml of tap water at 23ºC were subjected to microwave radiation for 7 minutes and 30 seconds, and observed for evidence of boiling (nucleation) and superheating (an abrupt stop in nucleation followed by an eruption). The tests were repeated using distilled water at 23ºC. The variables included changes in physical properties (different shaped containers, an artificially roughened container, the presence of a smooth probe, the presence of a boiling tab, the presence of an oily layer, and the presence of tea-leaf fragments) and chemical agents (additions of salt, sugar, and detergent to create solutions). Results Superheating was prevented physically by the presence of tea leaf fragments, the use of artificially roughened container, and boiling tab. Superheating was prevented chemically by the use of a detergent solution. Superheating occurred with the standard beaker, the wide container, the narrow container, the presence of a smooth probe, the presence of an oily layer, the use of an electrolytic (salt) solution, and the use of a sugar solution Conclusions/Discussion By preventing superheating physically, the artificially roughened container, the boiling tab, and the tea leaf fragments all physically facilitated nucleation. Similarly, by preventing superheating chemically, the detergent solution chemically facilitated nucleation. The other variables did not facilitate nucleation significantly. Nucleation therefore is the primary factor in the ability of water to superheat. Analysis of the data also illustrates the potential of chemical agents to alter the ability of water to nucleate, providing implications for the field of chemistry. The data also illustrates the viability of artificial roughening as a practical solution to enhance public safety.

Awards (1)

• Category Award

Competition history

• CSEF 2002 Physics & Astronomy · Entry S1516

Resources

• CSEF project summary ↗

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