Viewing a single comment thread. View all comments

piccadillyst t1_irnrw3m wrote

Reply to comment by taphead739 in Why, when you continue to burn ash, do the ashes eventually change from black to white? by genitalwaffles

Interestingly, most of these are basic oxides, meaning that they form very alcaline solutions in water. This was exploited in ancient times to prepare soap from fat.

174

l3lindsite t1_irnuzmt wrote

You're talking about deriving lye from ash in order to make soap. I was wondering about that. You said numerous metals end up getting oxidized in ash. So how does mixing ash with water give you lye specifically so you can combine with with fats and oils to make soap? How do you go from a random mix of oxidants to a specific alcaline chemical?

64

piccadillyst t1_irnxpe0 wrote

It's important not to mix up terms here. What you get after combustion are oxides: Na2O, CaO, K2O, MgO, etc (probably some superoxides as well, but I digress). These are not oxidants, because the metals are in very stable oxidation states. But they are very reactive towards water: the oxide anions "steal" protons from water, giving hydroxide ions as product. Specifically, in the case of K2O, the reaction would be something like: K2O + H2O ➡️2K+ + 2OH-. The hydroxide ions then react with triglycerides in the saponification reaction.

112

tregosmasher t1_irny4iy wrote

Lye is sometimes used to mean sodium hydroxide. If you bought lye from a chemical supply warehouse, that’s what you’d expect. Lye can also mean combining ash with water. You have conflated these two types of lye, which is incorrect. Wood ash lye is typically high in potassium hydroxide.

50

EdibleBatteries t1_iro9pl0 wrote

Hence why it is named “potassium” and not it’s symbolic kalium. It is found in high amounts in “pot ash”

41

EdibleBatteries t1_iro9x3i wrote

Hence why it is named “potassium” and not it’s symbolic kalium. It is found in high amounts in “pot ash”

13

alucardou t1_iroydfz wrote

The makers of "fireplace" bring you "potashium" Needed to make pot ash sound scientific, so they just put ium at the end. Brilliant.

17

Nixeris t1_irqnp3n wrote

When scientists discovered a metal that could be derrived from the roman alumin recipes, they called it Aluminium.

Found a metal in Magnesia? Call it Magnesium.

In California? Call it Californium.

The element is Blue-gray? Call it Blue-grayium. But make it fancy and use the Latin term for Blue-gray, 'Caesius'. Caesium or cesium.

10

Lurker_IV t1_irqlulr wrote

"ium" in the suffix that denotes a material. More than half of the elements end in 'ium'.

2

l3lindsite t1_irti3sl wrote

Okay so ignoring the ego tripping below what im gathering is pure lye is a particular chemical potassium hydroxide but wood ash has large amount of it in it so when you dillute it in water you are getting a mix of chemicals with a high concentration of lye within it, tho it isn't entirely pure lye. How could one refine this process.

1

hobopwnzor t1_irq7yyr wrote

This is why potassium has its name. It was isolated from pot-ash.

Pot-ash-ium.

7