Question #a6f2d

1 Answer
Sep 5, 2017

Answer:

#"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 %"#