Chemistry Question 6

Question

How many formula units of sodium chloride (NaCl) salt is produced from 18.0 g of sodium (Na)?

 

2 Na (s) + Cl₂ (g) --> 2 NaCl (s)

A. - 4.71 x 10²³ formula units of NaCl

B. - 9.43 x 10²³ formula units of NaCl

C. - 2.17 x 10²⁵ formula units of NaCl (Incorrect answer... )

D. - 1.08 x 10²⁵ formula units of NaCl

Please Explain your answer!

Answer 1

molar mass NaCl = 58.4 g /mol

atomic mass Na = 23.0 g /mol

2 Na (s) + Cl₂ (g) --> 2 NaCl (s)

18.0 g Na x 1 mol Na / 23.0 g = 0.783 mols Na

0.783 mols Na x 2 mol NaCl / 2 mol Na = 0.783 mols NaCl

0.783 mols NaCl x 6.02x10²³ form.units / mol = 4.71x10²³ formula units of NaCl (ANSWER A)