"Don't you feel sorry for catalysts?"
Kana suddenly said.
Milia tilted her head. "Sorry?"
"Because they just help but don't change themselves."
Rei smiled. "That's the definition of catalyst."
"But if catalysts had feelings, they might get jealous."
Toma laughed. "Just watching substrate turn into product."
Milia went along. "Interesting perspective. Let's think from the catalyst's feelings."
Rei drew on the whiteboard. "A + B → C, in the presence of catalyst."
"Catalyst brings A and B together."
Kana continued. "Cupid?"
"Good metaphor," Milia acknowledged. "But Cupid can't attend the wedding."
"That's the reason for jealousy."
Toma asked. "Does the catalyst really not change?"
Rei answered. "Returns to the same chemical state before and after the reaction."
"What about during?"
"Changes during. Sometimes forms intermediates."
Milia supplemented. "But eventually returns to original. That's the catalyst's condition."
Kana wrote in her notebook. "Catalyst = helps without changing."
"How does it help?" Toma asked.
"Lowers activation energy," Rei explained.
"Lowers the barrier."
"Makes it easier for substrate to cross the mountain."
Milia drew a diagram. "Pathway without catalyst and pathway with catalyst."
"The pathway with catalyst has a lower mountain."
Kana understood. "That's why reaction becomes faster."
"But," Rei emphasized, "equilibrium position doesn't change."
"Doesn't change?" Toma was confused.
"Both forward and reverse reactions are accelerated by the same factor."
"So the final amount of product is the same."
Kana thought. "Then what's the point of catalyst?"
"Time," Milia answered immediately. "Can make a reaction taking one year happen in one second."
"Industrially, that's everything."
Toma asked for examples. "Specifically?"
Rei enumerated. "Haber-Bosch process. Ammonia from nitrogen and hydrogen."
"Not practical without iron catalyst."
"Automobile catalytic converters," Milia added. "Decompose harmful substances in exhaust."
"Platinum, palladium, rhodium."
Kana was surprised. "Expensive metals."
"But small amounts suffice. Can be reused."
Toma asked. "Are enzymes catalysts too?"
"Biological catalysts," Rei answered. "But special catalysts."
"What's special?"
Milia explained. "Very high specificity. Catalyze only one reaction."
"Metal catalysts are more broad-spectrum."
Rei continued. "Enzymes work under mild conditions. Room temperature, atmospheric pressure, neutral pH."
"Industrial catalysts often require high temperature and pressure."
Kana summarized. "Enzymes = gentle catalysts."
"And controllable," Milia added.
"Controllable?"
"Feedback inhibition. When product is abundant, enzyme stops."
Rei drew a diagram. "Final product of metabolic pathway inhibits the first enzyme."
"Self-control system."
Toma was impressed. "Smart."
"Result of evolution," Milia said.
Kana returned to the original topic. "So, is the catalyst jealous?"
"Maybe," Toma laughed. "Work hard but don't get appreciated."
"Unsung hero."
Milia defended. "But without catalysts, nothing proceeds."
"Shadow protagonist."
Rei said quietly. "Scientists are like that too."
"Huh?" Kana asked back.
"Research results remain, but researchers' names are forgotten."
"But that's fine. If knowledge progresses."
Milia nodded. "Catalyst philosophy."
Toma declared. "I want to be like a catalyst."
"Help people, don't change myself."
Kana corrected. "It's okay to change a little, right?"
"Catalysts aren't perfect either," Rei acknowledged.
"Gradually deteriorate. Get poisoned."
"But can sometimes be regenerated."
Milia smiled. "Humans can regenerate too."
Outside the window, wind blew. Invisible, but certainly working. Like a catalyst.