Collapsed Chemical Knowledge: "Reaction Energy Moves Molecules"

Conversion of Reaction Energy into Mechanical Energy
Common Belief That Chemical Reaction Energy Is Released as Heat Collapses

Reaction equation of the Click reaction used in the experiment. A catalyst is involved. (B) Detailed reaction process. (C) Changes in the diffusion coefficients of each reactant and catalyst observed by nuclear magnetic resonance imaging. The pattern of diffusion coefficient decrease is clearly distinguishable according to reaction time.

[Asia Economy Reporter Junho Hwang] A study has revealed that molecules of reactants move faster after a typical chemical reaction. This research overturns the conventional wisdom that the energy generated during a chemical reaction does not affect molecular movement. It is expected to contribute to research on microscale robots requiring power in the microscopic world and drug delivery. Steve Granick, head of the Advanced Soft Matter Research Group at the Institute for Basic Science, and Research Fellow Juan Wang announced that these findings were published on the 30th (local time) in the international academic journal Science.

Chemical Reaction Energy Moves Molecules

(A) Microfluidic chip experimental environment where the catalyst concentration increases toward the right, while the concentrations of reactants and solvent (label) remain constant. (B) Solvent concentration gradient generated in (A). It shifts toward the left, where the catalyst concentration is low. (C) As a control experiment, a reactant concentration gradient was applied to create an environment where more reaction occurs on the right. However, the solvent concentration gradient observed in the catalyst gradient is absent.

The research team confirmed that molecules gain propulsion after a typical chemical reaction and move randomly by colliding with surrounding molecules.

During a chemical reaction, molecules break existing bonds between atoms and form new bonds, transforming into different substances. The reaction energy generated at this time is dissipated as localized heat (heat release theory), which is the established theory. It means that chemical reactions do not affect molecular movement.

However, the research team tracked molecular movement following chemical reactions and discovered that molecular diffusion increases macroscopically. They analyzed this and demonstrated that reaction energy is converted into mechanical energy.

The team observed chemical reactions occurring in solvents using nuclear magnetic resonance to track the movement of each reactant molecule. Experimental results showed that molecular diffusion accelerates after the reaction, and this diffusion could not be explained by simulations of molecular movement caused by convection from heat release. This confirmed that reactants move by a power source other than heat.

Molecules More Active After Catalytic Reactions

Change in solvent diffusion coefficient according to reaction energy of different chemical reactions. Blue, red, and green dots represent catalytic reactions, forming steep graphs that coincide with each other. In contrast, orange, pink, and white represent non-catalytic general reactions, forming gentle graphs.

Additionally, the research team revealed that reactions involving catalysts cause a completely different form of molecular diffusion compared to typical chemical reactions. They analyzed diffusion rates in 15 different chemical reactions and confirmed that molecular diffusion rates in catalytic reactions were much higher than in reactions without catalysts.

The team prepared a microfluidic chip with non-uniform catalyst concentration and observed solvent movement inside it. The solvent moved toward the area with lower catalyst concentration, but such movement did not occur with reactant concentration gradients. This indicates that the catalyst itself causes molecular movement different from typical chemical reactions, according to the research team’s explanation. A microfluidic chip refers to a chip that controls liquid flow inside microchannels with diameters in the micrometer range to process samples.

The research team expects this study to be used as a power source for medical microscale robots or applied in drug delivery research.

Steve Granick explained, "The reactions confirmed in this experiment are commonly used in plastic production and biomedical engineering, and controlling molecular movement here has significant economic value." Research Fellow Juan Wang said, "It can help understand self-moving materials existing in nature and contribute to creating sophisticated microscale machines."

This content was produced with the assistance of AI translation services.