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

1 Answer
Feb 29, 2016

Answer:

#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#.