Question

Calculate the mass percent composition of carbon in each the following carbon compounds (Using 4 sig figs) A C2H2 B C4H8 C C3H8 D C4H10O

Answer 1

A)

Molar mass of C2H2,

MM = 2*MM(C) + 2*MM(H)

= 2*12.01 + 2*1.008

= 26.036 g/mol

MM of C2H2 = 26.036

Lets calculate the mass of element

mass of C = 2*MM(C)

= 24.02 g

Mass % of C = (24.02*100)/26.036

= 92.3 %

B)

Molar mass of C4H8,

MM = 4*MM(C) + 8*MM(H)

= 4*12.01 + 8*1.008

= 56.104 g/mol

MM of C4H8 = 56.104

Lets calculate the mass of element

mass of C = 4*MM(C)

= 48.04 g

Mass % of C = (48.04*100)/56.104

= 85.6 %

C)

Molar mass of C3H8,

MM = 3*MM(C) + 8*MM(H)

= 3*12.01 + 8*1.008

= 44.094 g/mol

MM of C3H8 = 44.094

Lets calculate the mass of element

mass of C = 3*MM(C)

= 36.03 g

Mass % of C = (36.03*100)/44.094

= 81.7 %

D)

Molar mass of C4H10O,

MM = 4*MM(C) + 10*MM(H) + 1*MM(O)

= 4*12.01 + 10*1.008 + 1*16.0

= 74.12 g/mol

MM of C4H10O = 74.12

Lets calculate the mass of element

mass of C = 4*MM(C)

= 48.04 g

Mass % of C = (48.04*100)/74.12

= 64.8 %