Avogadro's Number

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Problem

Calculate the mass in grams of a single carbon (C) atom.

Solution

To calculate the mass of a single atom, first look up the atomic mass for carbon from the Periodic Table. This number, 12.01, is the mass of one mole of carbon. One mole of carbon is 6.022 x 10²³ atoms of carbon (Avogadro's number). This relation is then used to 'convert' a carbon atom to grams:

mass C atom = 1 C atom x 12.01 g / 6.022 x 10²³ C atoms = 1.994 x 10^-23 g

Answer

1.994 x 10^-23 g

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