Chapter 5, Problem 58E

Discrepancies in the experimental values of the molarmass of nitrogen provided some of the first evidence forthe existence of the noble gases. If pure nitrogen is collectedfrom the decomposition of ammonium nitrite,
${\text{NH}}_{\text{4}}{\text{NO}}_{\text{2}}\text{(}s\text{) }\stackrel{\text{Heat}}{\to }{\text{ N}}_{\text{2}}\text{(}g{\text{)+2H}}_{\text{2}}\text{O(}g\text{)}$

its measured molar mass is 28.01. If ${\text{O}}_{\text{2}}{\text{, CO}}_{\text{2}}{\text{, and H}}_{\text{2}}\text{O}$ are removed from air, the remaining gas has an averagemolar mass of 28.15. Assuming this discrepancy is solelya result of contamination with argon (atomic mass $=39.95$ ), calculate the ratio of moles of Ar to moles of ${\text{N}}_{\text{2}}$ in air.