The table shows the percentages of hydrocarbons that are found in a sample of crude oil.
| Hydrocarbons | Percentage |
|---|---|
| paraffins | 30 |
| naphthenes | 49 |
| aromatics | 15 |
| asphaltics | 6.0 |
Based on the given information, what is the best classification for this sample of crude oil?
A. an element
B. a pure compound
C. a pure substance
D. a mixture
Answer (1)
Crude oil consists of different hydrocarbons: paraffins, naphthenes, aromatics, and asphaltics.
An element consists of only one type of atom, a pure compound consists of fixed ratio of atoms, and a pure substance is either an element or a pure compound.
A mixture consists of two or more substances physically combined.
Therefore, crude oil is best classified as a mixture .
Explanation
Analyze the problem and data We are given the composition of a crude oil sample in terms of the percentages of different hydrocarbons: paraffins (30%), naphthenes (49%), aromatics (15%), and asphaltics (6%). The question asks us to classify the crude oil sample as either an element, a pure compound, a pure substance, or a mixture.
Define the classifications Let's define each of the possible classifications:
Element: A substance consisting of only one type of atom (e.g., gold, oxygen).
Pure compound: A substance consisting of two or more types of atoms chemically bonded in a fixed ratio (e.g., water, carbon dioxide).
Pure substance: A substance with a fixed chemical composition. This can be either an element or a pure compound.
Mixture: A substance consisting of two or more different substances that are physically combined but not chemically bonded (e.g., air, crude oil).
Determine the classification Crude oil is composed of various hydrocarbons, including paraffins, naphthenes, aromatics, and asphaltics, each present in different percentages. Since crude oil contains multiple substances that are not chemically bonded, it is best classified as a mixture.
State the final answer Therefore, based on the given information, the best classification for this sample of crude oil is a mixture.
Examples
Crude oil refining is a practical example where understanding the composition of mixtures is crucial. Different hydrocarbons in crude oil have different boiling points. By heating crude oil and separating the vapors, we can isolate valuable components like gasoline, kerosene, and diesel. This separation process relies on the fact that crude oil is a mixture, allowing us to extract and utilize its various components for different purposes.
