Question

A compound is formed when 9.03 g Mg combines completely with 3.48 g N. What is the percent composition of this compound?

Answer 1

The composition is `"72.2 % Mg"` and `"27.8 % N"` by mass.

Explanation:

The formula for percent composition is

`"% by mass" = "mass of a component"/"total mass" × 100 %`

You have `"9.03 g Mg"` and `"3.48 g N"`, so

`"total mass = (9.03 + 3.48) g = 12.51 g"`

∴ `"% Mg" = (9.03 color(red)(cancel(color(black)("g"))))/(12.51 color(red)(cancel(color(black)("g")))) × 100 % =72.2 %`

`"% N" = (3.48 color(red)(cancel(color(black)("g"))))/(12.51 color(red)(cancel(color(black)("g")))) × 100 % = 27.8 %`

The composition is `"72.2 % Mg"` and `"27.8 % N"` by mass.