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

4

Step-by-step 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* 10^(23)`

Hence,

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

So,

`6.023* 10^(23)` molecules have a mass of 131.293+ n18.998 g

Also,

`1` molecules have a mass of
`((131.293+ n18.998))/(6.023* 10^(23))` g

So,

`5.0* 10^(20)` molecules have a mass of
`((131.293+ n18.998))/(6.023* 10^(23))* 5.0* 10^(20)` g

Also, given mass = 0.172 g

Thus,

`((131.293+ n18.998))/(6.023* 10^(23))* 5.0* 10^(20)=0.172`

`(18.998n+131.293)/(1204.6)=0.172`

`18.998n+131.293=207.1912`

`n=(75.8982)/(18.998)=4`

Thus, value of n is 4.