How Do You Calculate the Percent Composition of Dopamine?

[yuuri14]

% (by mass) composition

Homework Statement

Dopamine, C8 H11 O2 N is a neutroransmitter. Determine the percent (by mass) composition of each of the elements in dopamite.

Homework Equations

The Attempt at a Solution

8C atoms= 12 (12.0) = 44.0amu
11H atoms = 11 (1.0) = 11.0 amu
2O atoms = 2 (16.00) = 32.0 amu
1N atoms = 1 (14.01) = 14.01 amu
total: 101.01 amu

%C (8)(12.0 amu)
______________ = 95.0%
101.01
%H (11)(1.0 amu)
_____________ = 10.8%
101.01

%O (2)(16.00)
_______________ = 31.6%
101.01

%N (1)(14.01)
___________ = 13.8%
101.01
please help/tell me if its correct or not.

 

[Borek]

8*12 is not 44.

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[Norfonz]

As it were, your calculations indicate a higher mass than is possible.

C8 H11 O2 N

MW = 8*12 + 11 + 2*16 + 14 = 96 + 11 + 32 + 14 = 153