The molecular mass of sodium oxide (na2o) is a. 61.97894. b. 38.98917. c. 22.98977. d. 45.97954

Answer is: The molecular mass of sodium oxide is A. 61.97894.

M(Na₂O) = 2 · Ar(Na) + Ar(O).

M(Na₂O) = 2 · 22.98976 + 15.9994.

M(Na₂O) = 61.97894; molecular mass of sodium oxide.

Ar is relative atomic mass (the ratio of the average mass of atoms of a chemical element to one unified atomic mass unit) of an element.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%