How does the law of constant proportions apply to carbon dioxide?
It states that carbon dioxide always contains the same proportions of carbon and oxygen by mass.
The Law of Definite Proportions states that a compound always contains exactly the same proportion of elements by mass.
Thus, no matter where the carbon dioxide comes from, it always carbon and oxygen in the ratio by mass.
12.01 g of C to 32.00 g of O or
1.000 g of C to 2.664 g of O or
0.3753 g of C to 1.000 g of O or
27.29 % C to 72.71 % O