If two or more samples of a pure compound contain the same elements in the same proportion by mass, what is the conclusion? A .) The samples are from different compounds. b.) The samples are from the same element. C.) The samples are from different elements. D.) The samples are from the same compound.
The correct answer and explanation is:
The correct answer is D.) The samples are from the same compound.
Explanation:
The law of constant composition, also known as the law of definite proportions, states that a pure compound will always have the same elements present in the same proportions by mass, regardless of the source of the compound or the amount produced. This is a fundamental principle of chemistry and highlights the consistency in the chemical composition of a compound.
When two or more samples of a pure compound contain the same elements in the same proportion by mass, it indicates that the chemical formula of the compound is consistent across all samples. For example, water (H2O) always contains two hydrogen atoms for every oxygen atom, no matter where or how it is obtained. Similarly, carbon dioxide (CO2) always contains one carbon atom and two oxygen atoms, in the same proportion by mass.
The law of constant composition is important because it distinguishes compounds from mixtures. In a mixture, the proportions of the components can vary, so the elements involved might not be present in the same proportions. For example, a mixture of salt and sand can have varying amounts of each, depending on how much salt and sand are mixed together.
This law also helps to clarify the nature of compounds versus elements. Elements consist of only one type of atom, and their proportions do not change. Compounds, however, are formed when different types of atoms combine in fixed proportions. So, if two samples contain the same elements in the same proportions, they must be samples of the same compound, rather than from different compounds or elements.