My "scientists" use the basic elemental understanding of science.
When it comes to biology stuff, they think a dwarf has more earth element in them, that is why they are dour, hardy and slow. The elf has more air in their makeup, so is flighty, swift and aloof. So when he gives a healing potion, it is generally made up of elements in the right mix for the species in question. His haste potion will be diluted elemental fire and wind, with just enough earth and water to stop it killing the imbiber.
I make regular references to the "science" of astrology. He can't prepare a stoneskin potion today, because the moon is in decline. Of course, I mean that is just basic science, everybody knows that.
Explosions are made by forcing two elements that don't want to be together into the same form. So making fire act like earthen dust (sulfa, charcoal), then adding more fire to it (fuse) turns it back into fire rapidly, making the explosion. Saltpetre is made from earth that has been soaked in water and it hates it, it wants to expel the water, hence it can be made volatile.
My alchemist kept collecting the blood and urine of the party at every opportunity. He said it was important to gather their essential salts and distil their blood into making good healing potions. He smelt terrible.
Scientists see magic flow like electricity through runes. Think of a rune as simply a circuit board that makes the magic flow as required. Dispelling magic is just an EMP device.
I stay away from real physics and chemistry. The DM should not have to know any of that stuff. Don't try to McGyver stuff with real world knowledge. It can be fun playing up science from earlier times. My characters would use leeches, drink mercury for good health and smoke tabacco to "keep the lungs clear".
P.S. One thing I found super fun was to pretend that my spells did not have the intended effect at all. I would say "Stand back! I will scorch them all them with NAPALM!" Then I cast the Grease spell, not Fireball. "Dammit! That was Petroleum Jelly, not Jellied Petroleum! I'm going to kill that apprentice!"