What is the mass of table salt in 20.5 moles of the substance?

Given:
n (NaCl) = 20.5 mol

Find:
m (NaCl) -?

Solution:
1) Using the periodic system of D.I.Mendeleev, determine the molar mass of NaCl, which will be numerically equal to the relative molecular mass:
M (NaCl) = Mr (NaCl) = Ar (Na) + Ar (Cl) = 23 + 35.5 = 58.5 g / mol;
2) Calculate the mass of NaCl:
m (NaCl) = n (NaCl) * M (NaCl) = 20.5 * 58.5 = 1199.25 g.

Answer: The mass of NaCl is 1199.25 g.