4 ms·

Those are the mass numbers from the periodic table which are exact integers and chemists probably know in their heads. If you have to look up a 4-digit number,

Those are the mass numbers from the periodic table which are exact integers and chemists probably know in their heads. If you have to look up a 4-digit number, it's not easier to look up or use 12.01 u instead of 19.95 yg, especially with higher atomic masses where they're less integer-like, as you say. But using u involves more conceptual complexity because you're mixing two different mass units (u and g) in the same calculation. That's the part that's hard to do in your head. Chemistry students often struggle with this whole concept, which comes with a whole parallel collection of formulas and quantities to work with the alternative mass unit. They more easily understand SI prefixes which is just reusing an existing well-known concept. You don't need to struggle with doin math on very tiny numbers any more than electrical engineers have to struggle with picofarads and nanoseconds.

Ekaros 2y ago
Avogadro's constant or number makes things relatively simple as you can treat 1 gram as 1 u and just work in moles. You have 100 grams of something, divide that by u or g and get number of moles of stuff. If you need to add something to react with, just multiply the number you just calculated with u of other stuff and get a minimum amount you need in grams. It really doesn't matter that you have 6.02214097×10^23 things of something. Moles, grams and atomic units really only matter. You never go to yoctograms(btw defined in 1991). But instead deal with numbers above 1. Which is doable calculating by hand even. Avogadro is there just to tie 1 atomic mass unit to 1 gram. Technically you could do it all on kilo, hecto, deka, deci, milli, micro moles... Depending on scale you work. As long as you keep it constant... In the end it is just moving the deciman point in the weight.
- EnigmaFlare 2y ago
  Can you write out a specific calculation using Avogadro's number/moles/u/etc. so I can do the same without those and see if it's actually any easier? "treat 1 gram as 1 u and just work in moles" Surely that's no easier than treating 1 gram as 1 yocto-gram and just working in yotta-things. > You never go to yoctograms You can and it's both as easy as moles to work with and conceptually simpler. That's why I'm saying we don't need all the Avogadro's number stuff since we do already have yg even if nobody uses it. Just to be clear, I'm talking about how it could be done. You seem to be talking about how it is done. I'm not denying how people actually use it, just pointing out that it's a giant needlessly-complicated historical legacy.

Ekaros 2y ago

Avogadro's constant or number makes things relatively simple as you can treat 1 gram as 1 u and just work in moles. You have 100 grams of something, divide that by u or g and get number of moles of stuff. If you need to add something to react with, just multiply the number you just calculated with u of other stuff and get a minimum amount you need in grams. It really doesn't matter that you have 6.02214097×10^23 things of something. Moles, grams and atomic units really only matter. You never go to yoctograms(btw defined in 1991). But instead deal with numbers above 1. Which is doable calculating by hand even. Avogadro is there just to tie 1 atomic mass unit to 1 gram. Technically you could do it all on kilo, hecto, deka, deci, milli, micro moles... Depending on scale you work. As long as you keep it constant... In the end it is just moving the deciman point in the weight.

EnigmaFlare 2y ago
Can you write out a specific calculation using Avogadro's number/moles/u/etc. so I can do the same without those and see if it's actually any easier? "treat 1 gram as 1 u and just work in moles" Surely that's no easier than treating 1 gram as 1 yocto-gram and just working in yotta-things. > You never go to yoctograms You can and it's both as easy as moles to work with and conceptually simpler. That's why I'm saying we don't need all the Avogadro's number stuff since we do already have yg even if nobody uses it. Just to be clear, I'm talking about how it could be done. You seem to be talking about how it is done. I'm not denying how people actually use it, just pointing out that it's a giant needlessly-complicated historical legacy.