Question: how many atoms do you consume (on average) in a day

Sarah Montgomery answered on 30 Oct 2024: last edited 30 Oct 2024 10:17

Different foods have different numbers of atoms per gram, with hydrogen atoms being very light and iron atoms being much heavier.

Avogadro’s number, 6.022 x 10^23 is the number of molecules in a mole. You can use this to work out how many molecules you ate, and then if you know the chemical structure you can work out the number of individual atoms.

If I eat 342g of sugar (a lot!), this is 6.022 x 10^23 molecules of sugar because sugar has a molar mass of roughly 342g. Each sugar molecule contains 12 carbon atoms, 22 hydrogen atoms and 11 oxygen atoms, so 342g of sugar contains about 2.71 x 10^25 atoms in total. We probably eat several hundred grams of food per day in total, so on average it might be around 5 x 10^25 atoms. Or written out, that’s 50,000,000,000,000,000,000,000,000 atoms.

If you add drinks it’s even more – a mole of water is only 18g, so a litre of water (1000g) is nearly 56 moles or about 3.35 x 10^25 molecules. Each molecule of water, H2O, is three atoms so a litre is about 10^26 atoms in total.