Answer
0.452 mol $HNO_{3}$.
Work Step by Step
Strategy: We have to convert mass to moles. So the conversion factor is 1 mol/Molar mass.
Moles in 28.5 g $HNO_{3}$
Molar mass $HNO_{3}$ =1 x 1.007 + 1 x 14.006 + 3 x 15.999
Molar mass $HNO_{3}$ = 63.01 g/mol
therefore:
28.5 g x $\frac{1 mol(HNO_{3})}{63.01 g($HNO_{3})}$ = 0.452 mol $HNO_{3}$
So 28.5 g $HNO_{3}$ is 0.452 mol $HNO_{3}$.
