Question

Which is the formula mass of Na2SO4?

119.06 amu
125.98 amu
142.05 amu
174.12 amu

Answer 1

Answer: 142.05 amu

Explanation:-

Formula mass is the amount of a compound with the same mass in grams as the formula mass in amu. It is calculated by adding the atomic masses of all the atoms contained in the formula.

Mass of Na = 22.98 amu

Mass of S = 32.06 amu

Mass of O = 15.99 amu

Thus formula mass of
`Na_2SO_4`= 2(22.99)+32.065+4(15.999)= 142.05amu

Answer 2

Ans: formula mass = 142.05 amu

Formula mass is the sum of the atomic masses of all the elements that comprise the molecule

Given molecule = Na2SO4

Atomic mass of Na = 22.989 amu

S = 32.065 amu

O = 15.999 amu

Formula mass = 2(Na) + S + 4(O)

= 2(22.989) + 32.065 + 4(15.999) = 142.039 amu