Answer to Question #117575 in General Chemistry for Hope

Question

A soap molecule has 18 carbon atoms. It contains 70.5% carbon, 11.5% hydrogen, and 10.4% oxygen by mass. It also contains one alkali metal cation. Identify the cation

Answer 1

% metal cation: 100 % - 70.5 % - 11.5 % - 10.4 % = 7.6 %

Mass of 18 carbon atoms = 18 × 12 a.m.u. = 216 a.m.u.

Proportion:

216 – 70.5 %

x – 7.6 %

x = 23.2 a.m.u.

Answer: Na⁺