Chemical quantities (AS)
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What is the molar mass of an element with an average atomic mass of 9.012 a.m.u. ?
Igloo writes
The molar mass of an element is the mass of one mole of its atoms or molecules. You have to specify which. The element with a mean atomic mass of 9.012 is beryllium, Be (see page 19 of the Nuffield Data Book).
Beryllium is a metal with a giant structure of atoms. The molar mass of its atoms is 9.012 g mol -1. The molar mass is numerically equal to the atomic mass in a.m.u.
In the case of chlorine, with an a.m.u. of 35.45, you have to be careful to state whether you are referring to chlorine atoms or chlorine molecules when stating its molar mass. The molar mass of chlorine molecules is 2 x 35.45 = 70.90 g mol-1.
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updated: 30 September 2004
