Question

A given sample of Xenon fluoride contains molecules of a single type $Xe{F}_n$ where $n$ is a whole number. If $9.03\times {10}^{20}$ molecules weight $0.311g$. What is $n$? Atomic weight of $Xe=131,F=19$.

Answer 1

Moles of $XeFn=\frac{9.03\times {10}^{20}}{6.023\times {10}^{23}}=1.5\times {10}^{-3}$

$⟹1.5\times {10}^{-3}=\frac{0.31}{131+19n}$

$⟹196.5+28.5n=310$

$⟹n=4$

Therefore, molecule is $Xe{F}_4$