What is percentage composition?

Jul 5, 2016

"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, $C {H}_{4.}$
${M}_{R} \left(C {H}_{4}\right) = 16.0 g m o {l}^{-} 1$

Mass of 1 mol of methane:
$m \left(C {H}_{4}\right) = n M = 1.00 m o l \cdot 16.0 g m o {l}^{-} 1 = 16.0 g$

Mass of hydrogen in 1 mol of methane:
$m \left(H\right) = n M = 4.00 m o l \cdot 1.00 g m o {l}^{-} 1 = 4.00 g$

Mass of carbon in 1 mol of methane:
$m \left(C\right) = n M = 1.00 m o l \cdot 12.0 g m o {l}^{-} 1 = 12.0 g$

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