understand that the Avogadro constant NA is the number of atoms in 0.012kg of carbon-12
use molar quantities where one mole of any substance is the amount containing a number of particles equal to the Avogadro constant NA
When we buy eggs from supermarket, instead of saying "may I have 24 eggs.... ", we tend to use the word "dozen" for convenience sake.
Similarly, particles often appear more than 1023 (even much much more). It would be kind of cumbersome to keeping saying 1023 this and 1023 that. Instead, we invent the idea "mole" to make our life easier (perhaps a bit harder for your exam?).
- The mole is the unit of measurement for amount of substance in the SI.
- One mole of particles is exactly 6.02214076×1023 particles : 1 mole ↔ 6.02214076×1023 particles
Furthermore, we invent the Avogadro constant NA in such a way:
- NA x ( 1 mole ) = 6.02214076×1023
There is no unit on the right hand side ! ( both side has no unit)
Numerically:
- NA = 6.02214076×1023 mol−1
- NA is also the number of atoms in 0.012kg of carbon-12 ! (Q: so how many atoms in 0.012kg of carbon-12? )
👉A: 1 mole by definition!
The Avogadro constant is just a factor converting mole into actual number of particles ;
- NA x (how many mole) = (actual number of particles)
Similar to 12 x (dozen) = (actual number of eggs)
Caution! In IGCSE CIE Physics, you need to know simple conversion of mole into actual particle number, and vice versa!
Reference:
Richard Woodside, Chris Mee - Cambridge International AS_A Level Physics Revision Education, 2nd Edition
David Sang, Graham Jones, Gurinder Chadha, Richard Woodside - Cambridge International AS and A Level Physics Coursebook, 2nd Edition
That's all, see you next time! 🤘
Reference:
Richard Woodside, Chris Mee - Cambridge International AS_A Level Physics Revision Education, 2nd Edition
David Sang, Graham Jones, Gurinder Chadha, Richard Woodside - Cambridge International AS and A Level Physics Coursebook, 2nd Edition