Question

What is percentage composition?

Answer 1

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

Explanation:

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`