A container of table salt has about 7.6 * 10^24 formula units of NaCI in it. What is the mass of the salt?

Answer 1

Use avogadro's # to first convert the # of formula units to moles.

7.6 x 10²⁴ formula units NaCl x (1 mol NaCl / 6.02 x 10²³ formula units NaCl) = 13 mol NaCl (to 2 significant figures)

Convert mol NaCl to g NaCl using its molar mass (58.44 g/mol)

13 mol NaCl x (58.44 g NaCl / 1 mol NaCl) = 760 g NaCl (to 2 significant figures)