Question #b148b

1 Answer
May 21, 2016

5.23×NA water molecules, where NA = Avogadro's number.

Explanation:

So two questions.

(i) What is NA, and,

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

Avogadro's number, NA = 6.022×1023.

So was this number plucked out of the air? In fact, it turns out that NA 1H atoms have mass of 1g precisely, and NA 16O atoms have mass of 16g 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 NA water molecules have a mass of 18.02g, what is the mass of your quantity?