Final answer:
The law of definite proportions states that a given chemical compound always contains the same elements in the exact same proportions by mass. The law of multiple proportions states that whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.
Step-by-step explanation:
The law of definite proportions states that a given chemical compound always contains the same elements in the exact same proportions by mass. For example, water (H2O) always contains two hydrogen atoms for every one oxygen atom. This means that the mass ratio of hydrogen to oxygen in water will always be 2:1.
The law of multiple proportions, on the other hand, states that whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers. For example, carbon and oxygen can form two different compounds: carbon monoxide (CO) and carbon dioxide (CO2). The mass ratio of carbon to oxygen in carbon monoxide is 1:1, while the mass ratio of carbon to oxygen in carbon dioxide is 1:2.
In summary, the law of definite proportions deals with the fixed ratios of elements within a compound, while the law of multiple proportions deals with the ratios between different compounds formed by the same elements.