"The purple disappeared..."
Kana stared at the beaker. The vivid purple of the potassium permanganate Toma added was turning transparent.
"Redox reaction," Rei explained. "The permanganate ion is stealing electrons."
Toma got excited. "Color change is so cool!"
"Why is it purple?" Kana asked.
Rei drew a diagram. "Manganese oxidation state is +7. This MnO4- in this state absorbs purple light."
"Oxidation state?"
"Electron attribution state. How electrons are counted from manganese's perspective."
Toma supplemented. "+7 means it lacks electrons. So it wants them."
"Wants electrons?" Kana laughed.
"That's the essence of oxidizing agents," Rei said seriously. "Substances that steal electrons from others."
Kana wrote in her notebook. "Oxidizing agent = accepts electrons."
"Right. Conversely, the one giving electrons is the reducing agent."
Toma added another reagent. "Let's try adding oxalic acid."
The purple became even lighter.
"Oxalic acid gave electrons," Rei explained. "Manganese oxidation state drops from +7 to +2."
"+2?"
"Mn2+. Colorless state."
Kana understood. "That's why it became transparent."
"Technically pale pink," Toma corrected. "But compared to purple, it's invisible."
Rei wrote the reaction equation. "MnO4- + 8H+ + 5e- → Mn2+ + 4H2O"
"Needs eight hydrogen ions and five electrons."
Kana calculated. "It accepts five electrons?"
"+7 to +2, so five electrons move."
Toma added. "That's why permanganate is a strong oxidizing agent."
"Strong?"
"Strong electron-stealing power. High ability to oxidize others."
Kana asked. "What happens when electrons move?"
Rei thought. "Physically, orbitals change. Electrons from oxalic acid enter manganese orbitals."
"Orbitals?"
"Regions where electrons can exist. Each atom has different shapes."
Toma continued the experiment. "Let's change the pH."
In acidic solution, purple disappeared quickly; in neutral, slowly.
"pH changes reaction rate," Kana noticed.
"Right. Look at the equation," Rei pointed. "H+ is needed for the reaction."
"More hydrogen ions make the reaction proceed easier?"
"Correct. H+ is part of the reaction's driving force."
Toma took out another reagent. "Now with iron ions."
Adding permanganate to the green solution. Purple disappeared again.
"Fe2+ oxidized to Fe3+," Rei explained.
Kana noticed the pattern. "Permanganate always steals electrons."
"Exactly. That's why it has a cold gaze," Toma said poetically.
"Cold?"
"Mercilessly stealing electrons. Changing the other's state."
Rei nodded. "Oxidation is losing electrons. The moment a substance's properties change."
Kana stared into the beaker. The invisible flow of electrons.
"Are electrons really moving?"
"Quantum mechanically it's complex," Rei admitted. "But we can observe it as changes in oxidation states."
Toma laughed. "Seeing the invisible through color. That's chemistry's beauty."
Kana murmured. "The purple gaze saw through the electrons."
"And steals them," Rei said quietly.
The three imagined the invisible journey of electrons. The purple of permanganate was the color of hunger for electrons.