Question

A sample of a compound of xenon and fluorine contains molecules of a single type; XeFn, where n is a whole number. If 5.0 x 1020 of these XeFn molecules have a mass of 0.172 g, what is the value of n?

Answer 1

Answer:

4

Explanation:

Avogadro’s number represent the number of the constituent particles which are present in one mole of the substance. It is named after scientist Amedeo Avogadro and is denoted by $N_0$.

Also, it is the number of particles in exactly 12.000 g of isotope carbon 12.

Avogadro constant:-

$N_a=6.023\times 10^{23}$

Hence,

Mass of $XeF_n$ = 131.293+ n18.998 g

So,

$6.023\times 10^{23}$  molecules have a mass of 131.293+ n18.998 g

Also,

$1$  molecules have a mass of $\frac{(131.293+ n18.998)}{6.023\times 10^{23}}$ g

So,

$5.0\times 10^{20}$  molecules have a mass of $\frac{(131.293+ n18.998)}{6.023\times 10^{23}}\times 5.0\times 10^{20}$ g

Also, given mass = 0.172 g

Thus,

$\frac{(131.293+ n18.998)}{6.023\times 10^{23}}\times 5.0\times 10^{20}=0.172$

$\frac{18.998n+131.293}{1204.6}=0.172$

$18.998n+131.293=207.1912$

$n=\frac{75.8982}{18.998}=4$

Thus, value of n is 4.