To classify the given sample of crude oil, let's carefully examine the provided data and definitions relevant to the question.
### Step-by-Step Analysis:
1. Data Summary:
The provided table lists the percentages of various hydrocarbons in a crude oil sample:
- Paraffins: 30%
- Naphthenes: 49%
- Aromatics: 15%
- Asphaltics: 6.0%
2. Definitions:
- Element: A substance consisting of only one type of atom. For example, hydrogen (H), oxygen (O), or gold (Au). An element cannot be broken down into simpler substances by chemical means.
- Pure Compound: A substance composed of two or more different elements chemically bonded in fixed proportions. Examples include water (H₂O) and carbon dioxide (CO₂). A pure compound has consistent properties and composition throughout.
- Pure Substance: This term can refer either to an element or a pure compound. It signifies a material with a constant composition and consistent properties.
- Mixture: A physical combination of two or more substances where each retains its own chemical identity and properties. Mixtures can be homogeneous (uniform composition) or heterogeneous (non-uniform composition). Examples include air, which is a homogeneous mixture of gases, or crude oil, which typically is a heterogeneous mixture of many hydrocarbons.
3. Application of Definitions to Data:
- Element: The crude oil sample cannot be an element because it is composed of multiple hydrocarbons (not a single type of atom).
- Pure Compound: The sample contains multiple hydrocarbons in varying proportions, not a single type of compound with fixed proportions. Thus, it is not a pure compound.
- Pure Substance: This includes elements and pure compounds, neither of which describes the given sample. Therefore, the sample is not a pure substance.
- Mixture: The sample consists of several different hydrocarbons (paraffins, naphthenes, aromatics, and asphaltics) mixed together. Each component retains its properties and does not chemically bond with others to form a single substance.
### Conclusion:
Given the percentages of various hydrocarbons, the substance in the crude oil sample retains the defining characteristics of a mixture, where multiple components are physically combined without forming new chemical bonds among them.
Therefore, the best classification for this sample of crude oil is:
a mixture.
