Question #b148b

1 Answer
May 21, 2016

5.23xxN_A " water molecules", where N_A = "Avogadro's number".

Explanation:

So two questions.

(i) What is N_A, and,

(ii) Why should we use such an absurdly large number?

Avogadro's number, N_A = 6.022xx10^23.

So was this number plucked out of the air? In fact, it turns out that N_A ""^1H" atoms" have mass of 1*g precisely, and N_A ""^16O" atoms" have mass of 16*g precisely.

Avogadro's number is thus the link between grams and kilograms, that which we can weigh and measure in the lab, and the micro world of atoms and molecules, that of which we can theorize and conceive.

If N_A water molecules have a mass of 18.02*g, what is the mass of your quantity?