Question

Calculate the mass percent of carbon,oxygen, nitrogen and hydrogen in acetamide, C2H5NO.

Molar Mass:
O=16, N=14,C=12, H =1.

Answer 1

40.68 % C

23.73 % N

8.47% H

27.12% O

Step-by-step explanation:

The mass percent of an element X in a compound is calculated as the molar mass (MM) of X multiplied by the number of atoms of X in the compound, divided into the molecular weight (MW) of the compound, as follows:

mass percent of X = (MM(X) x number of atoms of X)/MW compound x 100

Thus, we first calculate the MW of acetamide (C₂H₅NO) by using the molar mass of the chemical elements C, H, N and O:

MW(C₂H₅NO) = (12 g/mol C x 2) + (1 g/mol H x 5) + 14 g/mol N + 16 g/mol O = 59 g/mol

Now, we can calculate the mass percent of each element (C, H, N, O) in C₂H₅NO:

• Mass percent of C (2 atoms of C in 1 molecule of C₂H₅NO):

% mass C = (12 g/mol x 2)/(59 g/mol) x 100 = 40.68 %

• Mass percent of N (1 atom of N in 1 molecule of C₂H₅NO):

% mass N = (14 g/mol x 1)/(59 g/mol) x 100 = 23.73 %

• Mass percent of H (5 atoms of H in 1 molecule of C₂H₅NO):

% mass H = (1 g/mol x 5)/(59 g/mol) x 100 = 8.47 %

• Mass percent of O (1 atom of O in 1 molecule of C₂H₅NO):

% mass O = (16 g/mol x 1)/(59 g/mol) x 100 = 27.12 %

The sum of the mass percents has to be equal to 100%:

40.68 % C + 23.73 % N + 8.47% H + 27.12% O = 100%