Question

Which is the formula mass of Na2SO4?
answers are
119.06 amu125.98 amu142.05 amu174.12 amu

Answer 1

Formula mass of Na2SO4 = 2 x atomic mass of Na + atomic mass of S + 4 x atomic mass of O.
 
                                            =  2x22.99 + 32.065 + 4x15.999
                                            =           142.041
                                            ~             142.05 amu

Hope this helps!

Answer 2

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 the sum of 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 $Na_2SO_4= 2(22.98)+32.06+4(15.99)= 142.05amu$