The mass percent of a molecule shows the amount each element contributes to the total molecular mass.
The first step in determining the mass percent of a given molecule is to determine each of the molecule component atoms’ . Since acetamine is composed of carbon nitrogen oxygen and hydrogen we get
##Molar## ##mass_(carbon)## = 12.0 g/mol
##Molar## ##mass_(nitrog en)## = 14.0 g/mol
##Molar## ##mass_(o xyg en)## = 16.0 g/mol
##Molar## ##mass_(hydrog en)## = 1.00g/mol
Each element’s mass contribution is determined by multiplying the number of atoms of a certain element with its molar mass
Carbon contributes ##2 * 12.0 = 24.0## g/mol;Nitrogen contributes ##1 * 14.0 = 15.0## g/mol;Oxygen contributes ##1*16.0 = 16.0## g/mol;Hydrogen contributes ##5*1.00 = 5.00## g/mol
Adding each element’s contribution gives us the molecule’s total
##molarmass_(C_2H_5NO) = 24.0 + 15.0 + 16.0 + 5.00=59## g/mol
The final step to determining the molecul’s mass percent is to divide each elemnt’s contribution by acetamide’s molar mass and to multiply the result by 100%
Mass percent of Carbon = ##24.0/59.0 * 100% = 40.7%##
Mass percent of Nitrogen = ##14.0/59.0 * 100% = 23.7%##
Mass percent of Oxygen = ##16.0/59.0 * 100% = 27.1%##
Mass percent of Hydrogen = ##5.00/59.0 = 8.50%##
Always check the validity of the answer by adding up all the percentages
##40.7 + 23.7 + 27.1 + 8.50 = 100%##
So acetamide is 40.7% Carbon 23.7% Nitrogen 27.1% Oxygen and 8.5% Hydrogen…