What is percentage composition?

Question

7022 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-07-05T08:47:17

"Percentage composition is the percentage by mass of each element present in a compound" - www.chemteam.info

An example of this follows:

Find the percentage compositions of carbon and hydrogen in methane, $CH_4.$
$M_R(CH_4)=16.0gmol^-1$

Mass of 1 mol of methane:
$m(CH_4)=nM=1.00mol*16.0gmol^-1=16.0g$

Mass of hydrogen in 1 mol of methane:
$m(H)=nM=4.00mol*1.00gmol^-1=4.00g$

Mass of carbon in 1 mol of methane:
$m(C)=nM=1.00mol*12.0gmol^-1=12.0g$

Percentage mass of hydrogen in 1 mol of methane:
$=(4.00g)/(16.0g)*100%=25%$

Percentage mass of carbon in 1 mol of methane:
$=(12.0g)/(16.0g)*100%=75%$

Percentage composition of methane:
$25% H, 75% C$