A recipe for chili calls for 3 g of sodium chloride. How many formula units of NaCl is that?

1 Answer
David G.
Feb 29, 2016

3 g is 0.075 mol of NaCl. Multiply this by Avogadro's number to find that this amount of salt contains 4.5xx10^22 formula units of NaCl.

Explanation:

First find the number of moles.

The molar mass is 23+17=40 gmol^-1, so n=m/M=3/40=0.075 mol.

Now one mole of any substance contains Avogadro's number, 6.02xx10^23 units of that substance: in this case formula units (one Na and one Cl) of NaCl.

That means the 3 g of salt (and therefore the chili) will contain 4.5xx10^22 formula units of NaCl.

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