Question

Question #a6f2d

Answer 1

`"NH"_3` contains 82.25 % `"N"` by mass.

Explanation:

The formula for mass percent is

`color(blue)(barul|stackrel(" ")("Mass %" = "mass of component"/"total mass" × 100 %)|)`

Let's assume that we have 1 molecule of `"NH"_3`.

Then we have 1 atom of `"N"` and 3 atoms of `"H"`.

We can use the Periodic Table to compute the masses:

`bbul("No."color(white)(m)"Atom"color(white)(m)A_text(r)color(white)(ml)"Mass")`
`color(white)(ll)1color(white)(mmml)"N"color(white)(ml)14.01color(white)(m)14.01`
`ul(color(white)(ll)3color(white)(mmml)"H"color(white)(mlll)1.008color(white)(m)3.024`
`color(white)(mmmmmml)"Total = 17.034"`

∴ `"Mass % N" = 14.01/17.034 × 100 % = 82.25 %"`