• Question: how many atoms are they made of

    Asked by samuel05 to Catshark on 9 Nov 2017.
    • Photo: Lesser-Spotted Catshark

      Lesser-Spotted Catshark answered on 9 Nov 2017:

      This question is a bit beyond my expertise but I’ll give it a go! You may have learned in chemistry or physics that the number of atoms in one mol of a substance (Avogadro’s number) is 6.023 × 10^23. Animals are mostly made of water (H20) so I’m going to simply catsharks (just a bit) and assume they are ONLY water…the molecular weight of water is 18.02 grams/mol and an average catshark weighs about 1 kilogram…you get (18.02 g/mol) x (1kg/1000g) = 55.49 mol. Multiply that by Avogadro’s number: (55.49mol) x (6.02×10^23 atoms/mol) = 3.34×10^25 atoms. Plus or minus a few billion atoms…