Answer to Question #132366 in General Chemistry for AnnMarie Dimian

Question

Consider two compounds, A and B, that contain only carbon and oxygen. Compound A has a mass ratio of carbon to oxygen of 1.33, and Compound B has a mass ratio of carbon to oxygen of 1.66. Are these results consistent with the law of definite proportions?If you would like full credit, you must support your answer.

Answer 1

The law of definite proportions, also known as the law of constant composition suggests that a chemical compound always contains the same elements combined together in the same proportions by mass.

Both the compounds A and B conform to the law of definite proportion.

Dividing the mass of oxygen per g of carbon of compound B;

$1.66\over 1.33$ $=1.2=1$

Hence the masses of Oxygen combine with the masses of Carbon in the ratio of $1:1$ which is consistent with the ratio of definite proportions.