Sulfur trioxide reacts with water to form sulfuric acid according to the

Question

following reaction: SO3 + H2O
H2SO4

Given the atomic mass of hydrogen is 1 amu, the atomic mass of oxygen is 16 amu, and one
molecule of sulfuric acid has a mass a of 98 amu, what is the atomic mass of sulfur trioxide?

-116 amu

-80 amu

-48 amu

-32 amu

Answer 1

H2SO4 has mass 2*1 + 1S + 4*16 = 98
so S = 98-64-2 = 32
SO3 has mass 32+3*16 = 80

or,
SO3 = H2SO4 - (H2O) = 98 - (2+16) = 80