Redefining Avogadro's Number. A mole is the number of molecules in a gram of water: ~6.022 x 10
23. Unfortunately "a gram" is defined by
a chunk of metal in
a vault in France, the last of the seven SI units still defined by a physical artifact. Since the reference mass (known as "Le Gran K") is actually
changing over time (due to cleaning, handling, etc), the definition of a gram is currently temporally unstable.
Now a new proposal has been put forward to explicitly define the number to be a known integer: 602,214,141,070,409,084,099,072, which would fundamentally change the way we define a gram. Le Gran K could become a historical curiosity like
the original platinum meter stick.
posted by dkg
on Mar 2, 2007 -
39 comments
