What is the mass of 500 molecules of #"NaCl"#?

1 Answer
Truong-Son N.
Aug 4, 2017

There is no such thing as an ionic molecule, so I will instead calculate for #"500 formula units"#...

#"500 equiv. NaCl" xx ("1 mol")/(6.0221413 xx 10^(23) "things")#

#= 8.303 xx 10^(-22) "mols NaCl"#

(what is this #6.0221413 xx 10^(23)# number called?)

And each #"mol"# has a characteristic molar mass of #22.989 + 35.453 = "58.442 g"#, using the periodic table for #"Na"# and #"Cl"# (what are their names?).

As a result, the mass is:

#8.303 xx 10^(-22) cancel"mols NaCl" xx ("58.442 g")/(cancel"1 mol NaCl")#

#=# #ulcolor(blue)(4.852 xx 10^(-20) "g")#

Now, this number is absurdly small, but that should make sense, as we only have #500# particles, each a few nanometers in diameter, much, much less than a handful of salt formula units.

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