Answer
a) $C_2H_6O_2$
$M=62.07\ g/mol$
b) $C_3H_6O_3$
$M=90.08\ g/mol$
c) $C_6H_8O_6$
$M=176.12\ g/mol$
The molecule with the largest mass percents of both carbon and oxygen is ascorbic acid.
Work Step by Step
Atomic weights: $C: 12.011,\ H: 1.0079,\ O: 15.999$
a) $C_2H_6O_2$
$M=2\times12.011+6\times1.0079+2\times15.999=62.07\ g/mol$
Mass percents:
C: $2\times12.011/62.07\times100\%=38.70\%$
O: $2\times15.999/62.07\times100\%=51.55\%$.
b) $C_3H_6O_3$
$M=3\times12.011+6\times1.0079+3\times15.999=90.08\ g/mol$
Mass percents:
C: $3\times12.011/90.08\times100\%=40.00\%$
O: $3\times15.999/90.08\times100\%=53.28\%$
c) $C_6H_8O_6$
$M=6\times12.011+8\times1.0079+6\times15.999=176.12\ g/mol$
Mass percents:
C: $6\times12.011/176.12\times100\%=40.92\%$
O: $6\times15.999/176.12\times100\%=54.51\%$
The molecule with the largest mass percent of both carbon and oxygen is ascorbic acid.
