Grandma, science is good at making people have a sense of cognitive dissonance; the unpleasant internal contradictions felt when presented with the knowledge that is contrary to what one earlier perceived. Such a form of cognitive dissonance can give people a little trouble when they are attempting to comprehend why boiling is a cooling process attributable to existing preconceptions anchored in what people have experienced (Jiaqiang et al., 2018). Bringing water to a boil when making tea is a process that cools the water because it decreases its overall temperature.
You can convince your tea-time friends of the fascinating concept of boiling being a cooling process by first letting them understand that it begins with the transfer of heat from the flame of fire to the individual molecules of water. Heating makes each molecule of water to move increasingly fast as the kinetic energy in them grows (Kabeel et al., 2017). When the molecule of water acquires sufficient energy at the boiling point, it shoots out leaving the surface of the water through evaporation. If a molecule of water attempts to leave without adequate energy to overcome atmospheric pressure, it is kept down to roll around and gain more strength (Yuan et al., 2019). Boiling is deemed a cooling process since when the water reaches the critical point, heat escapes via speedy evaporation (Diaz & Guo, 2017). Fundamentally, boiling occurs the moment liquid turns into gas because as water molecules evaporate, they expel excess heat from the tea. When boiling, hot molecules escape from the teapot thus taking away some heat energy in the process (Khaidarov & Khaidarov, 2016). This decrease in the heat makes boiling a cooling progression.
Bringing water to a boil while making tea is a progression that cools it since the process lessens the overall temperature. Continued heating makes water molecules to move progressively fast as the kinetic energy in them rises. As vapor evaporates, it carries away heat hence translating to cooling of the water.
References
Diaz, R., & Guo, Z. (2017). Molecular dynamics study of wettability and pitch effects on maximum critical heat flux in evaporation and pool boiling heat transfer. Numerical Heat Transfer, Part A: Applications, 72(12), 891-903. Web.
Jiaqiang, E., Zhang, Z., Tu, Z., Zuo, W., Hu, W., Han, D., & Jin, Y. (2018). Effect analysis on flow and boiling heat transfer performance of cooling water-jacket of bearing in the gasoline engine turbocharger. Applied Thermal Engineering, 130, 754-766. Web.
Kabeel, A. E., Abdelgaied, M., & El-Said, E. M. (2017). Study of a solar-driven membrane distillation system: Evaporative cooling effect on performance enhancement. Renewable Energy, 106, 192-200. Web.
Khaidarov, G. G., & Khaidarov, A. G. (2016). The relationship between melting point, boiling point and critical point. Intellectual Archive, 5(2), 15-19.
Yuan, B., Zhang, Y., Liu, L., & Wei, J. (2019). Experimental research on subcooled flow boiling heat transfer performance and associated bubble characteristics under pulsating flow. Applied Thermal Engineering, 157, 1-13. Web.